// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/mm/page_alloc.c
 *
 *  Manages the free list, the system allocates free pages here.
 *  Note that kmalloc() lives in slab.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *  Swap reorganised 29.12.95, Stephen Tweedie
 *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
 *  Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999
 *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
 *  Zone balancing, Kanoj Sarcar, SGI, Jan 2000
 *  Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002
 *          (lots of bits borrowed from Ingo Molnar & Andrew Morton)
 */

#include <generated/deconfig.h> 
#include <linux/stddef.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/swap.h>
#include <linux/interrupt.h>
#include <linux/pagemap.h>
#include <linux/jiffies.h>
#include <linux/memblock.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/kasan.h>
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/pagevec.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/ratelimit.h>
#include <linux/oom.h>
#include <linux/topology.h>
#include <linux/sysctl.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/memory_hotplug.h>
#include <linux/nodemask.h>
#include <linux/vmalloc.h>
#include <linux/vmstat.h>
#include <linux/mempolicy.h>
#include <linux/memremap.h>
#include <linux/stop_machine.h>
#include <linux/random.h>
#include <linux/sort.h>
#include <linux/pfn.h>
#include <linux/backing-dev.h>
#include <linux/fault-inject.h>
#include <linux/page-isolation.h>
#include <linux/debugobjects.h>
#include <linux/kmemleak.h>
#include <linux/compaction.h>
#include <trace/events/kmem.h>
#include <trace/events/oom.h>
#include <linux/prefetch.h>
#include <linux/mm_inline.h>
#include <linux/migrate.h>
#include <linux/hugetlb.h>
#include <linux/sched/rt.h>
#include <linux/sched/mm.h>
#include <linux/page_owner.h>
#include <linux/kthread.h>
#include <linux/memcontrol.h>
#include <linux/ftrace.h>
#include <linux/lockdep.h>
#include <linux/nmi.h>
#include <linux/psi.h>
#include <linux/padata.h>
#include <linux/khugepaged.h>

#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
#include "internal.h"
#include "shuffle.h"
#include "page_reporting.h"

///* Free Page Internal flags: for internal, non-pcp variants of free_pages(). */
//typedef int __bitwise fpi_t;

///* No special request */
//#define FPI_NONE		((__force fpi_t)0)

///*
// * Skip free page reporting notification for the (possibly merged) page.
// * This does not hinder free page reporting from grabbing the page,
// * reporting it and marking it "reported" -  it only skips notifying
// * the free page reporting infrastructure about a newly freed page. For
// * example, used when temporarily pulling a page from a freelist and
// * putting it back unmodified.
// */
//#define FPI_SKIP_REPORT_NOTIFY	((__force fpi_t)BIT(0))

///*
// * Place the (possibly merged) page to the tail of the freelist. Will ignore
// * page shuffling (relevant code - e.g., memory onlining - is expected to
// * shuffle the whole zone).
// *
// * Note: No code should rely on this flag for correctness - it's purely
// *       to allow for optimizations when handing back either fresh pages
// *       (memory onlining) or untouched pages (page isolation, free page
// *       reporting).
// */
//#define FPI_TO_TAIL		((__force fpi_t)BIT(1))

///* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
//static DEFINE_MUTEX(pcp_batch_high_lock);
//#define MIN_PERCPU_PAGELIST_FRACTION	(8)

//#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
//DEFINE_PER_CPU(int, numa_node);
//EXPORT_PER_CPU_SYMBOL(numa_node);
//#endif

//DEFINE_STATIC_KEY_TRUE(vm_numa_stat_key);

//#ifdef CONFIG_HAVE_MEMORYLESS_NODES
///*
// * N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
// * It will not be defined when CONFIG_HAVE_MEMORYLESS_NODES is not defined.
// * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem()
// * defined in <linux/topology.h>.
// */
//DEFINE_PER_CPU(int, _numa_mem_);		/* Kernel "local memory" node */
//EXPORT_PER_CPU_SYMBOL(_numa_mem_);
//#endif

///* work_structs for global per-cpu drains */
//struct pcpu_drain {
//	struct zone *zone;
//	struct work_struct work;
//};
//static DEFINE_MUTEX(pcpu_drain_mutex);
//static DEFINE_PER_CPU(struct pcpu_drain, pcpu_drain);

//#ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY
//volatile unsigned long latent_entropy __latent_entropy;
//EXPORT_SYMBOL(latent_entropy);
//#endif

///*
// * Array of node states.
// */
//nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
//	[N_POSSIBLE] = NODE_MASK_ALL,
//	[N_ONLINE] = { { [0] = 1UL } },
//#ifndef CONFIG_NUMA
//	[N_NORMAL_MEMORY] = { { [0] = 1UL } },
//#ifdef CONFIG_HIGHMEM
//	[N_HIGH_MEMORY] = { { [0] = 1UL } },
//#endif
//	[N_MEMORY] = { { [0] = 1UL } },
//	[N_CPU] = { { [0] = 1UL } },
//#endif	/* NUMA */
//};
//EXPORT_SYMBOL(node_states);

atomic_long_t _totalram_pages __read_mostly;
EXPORT_SYMBOL(_totalram_pages);
//unsigned long totalreserve_pages __read_mostly;
//unsigned long totalcma_pages __read_mostly;

//int percpu_pagelist_fraction;
//gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
//#ifdef CONFIG_INIT_ON_ALLOC_DEFAULT_ON
//DEFINE_STATIC_KEY_TRUE(init_on_alloc);
//#else
//DEFINE_STATIC_KEY_FALSE(init_on_alloc);
//#endif
//EXPORT_SYMBOL(init_on_alloc);

//#ifdef CONFIG_INIT_ON_FREE_DEFAULT_ON
//DEFINE_STATIC_KEY_TRUE(init_on_free);
//#else
//DEFINE_STATIC_KEY_FALSE(init_on_free);
//#endif
//EXPORT_SYMBOL(init_on_free);

//static int __init early_init_on_alloc(char *buf)
//{
//	int ret;
//	bool bool_result;

//	ret = kstrtobool(buf, &bool_result);
//	if (ret)
//		return ret;
//	if (bool_result && page_poisoning_enabled())
//		pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, will take precedence over init_on_alloc\n");
//	if (bool_result)
//		static_branch_enable(&init_on_alloc);
//	else
//		static_branch_disable(&init_on_alloc);
//	return 0;
//}
//early_param("init_on_alloc", early_init_on_alloc);

//static int __init early_init_on_free(char *buf)
//{
//	int ret;
//	bool bool_result;

//	ret = kstrtobool(buf, &bool_result);
//	if (ret)
//		return ret;
//	if (bool_result && page_poisoning_enabled())
//		pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, will take precedence over init_on_free\n");
//	if (bool_result)
//		static_branch_enable(&init_on_free);
//	else
//		static_branch_disable(&init_on_free);
//	return 0;
//}
//early_param("init_on_free", early_init_on_free);

///*
// * A cached value of the page's pageblock's migratetype, used when the page is
// * put on a pcplist. Used to avoid the pageblock migratetype lookup when
// * freeing from pcplists in most cases, at the cost of possibly becoming stale.
// * Also the migratetype set in the page does not necessarily match the pcplist
// * index, e.g. page might have MIGRATE_CMA set but be on a pcplist with any
// * other index - this ensures that it will be put on the correct CMA freelist.
// */
//static inline int get_pcppage_migratetype(struct page *page)
//{
//	return page->index;
//}

//static inline void set_pcppage_migratetype(struct page *page, int migratetype)
//{
//	page->index = migratetype;
//}

//#ifdef CONFIG_PM_SLEEP
///*
// * The following functions are used by the suspend/hibernate code to temporarily
// * change gfp_allowed_mask in order to avoid using I/O during memory allocations
// * while devices are suspended.  To avoid races with the suspend/hibernate code,
// * they should always be called with system_transition_mutex held
// * (gfp_allowed_mask also should only be modified with system_transition_mutex
// * held, unless the suspend/hibernate code is guaranteed not to run in parallel
// * with that modification).
// */

//static gfp_t saved_gfp_mask;

//void pm_restore_gfp_mask(void)
//{
//	WARN_ON(!mutex_is_locked(&system_transition_mutex));
//	if (saved_gfp_mask) {
//		gfp_allowed_mask = saved_gfp_mask;
//		saved_gfp_mask = 0;
//	}
//}

//void pm_restrict_gfp_mask(void)
//{
//	WARN_ON(!mutex_is_locked(&system_transition_mutex));
//	WARN_ON(saved_gfp_mask);
//	saved_gfp_mask = gfp_allowed_mask;
//	gfp_allowed_mask &= ~(__GFP_IO | __GFP_FS);
//}

//bool pm_suspended_storage(void)
//{
//	if ((gfp_allowed_mask & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS))
//		return false;
//	return true;
//}
//#endif /* CONFIG_PM_SLEEP */

//#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
//unsigned int pageblock_order __read_mostly;
//#endif

//static void __free_pages_ok(struct page *page, unsigned int order,
//			    fpi_t fpi_flags);

///*
// * results with 256, 32 in the lowmem_reserve sysctl:
// *	1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
// *	1G machine -> (16M dma, 784M normal, 224M high)
// *	NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA
// *	HIGHMEM allocation will leave 224M/32 of ram reserved in ZONE_NORMAL
// *	HIGHMEM allocation will leave (224M+784M)/256 of ram reserved in ZONE_DMA
// *
// * TBD: should special case ZONE_DMA32 machines here - in those we normally
// * don't need any ZONE_NORMAL reservation
// */
//int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES] = {
//#ifdef CONFIG_ZONE_DMA
//	[ZONE_DMA] = 256,
//#endif
//#ifdef CONFIG_ZONE_DMA32
//	[ZONE_DMA32] = 256,
//#endif
//	[ZONE_NORMAL] = 32,
//#ifdef CONFIG_HIGHMEM
//	[ZONE_HIGHMEM] = 0,
//#endif
//	[ZONE_MOVABLE] = 0,
//};

//static char * const zone_names[MAX_NR_ZONES] = {
//#ifdef CONFIG_ZONE_DMA
//	 "DMA",
//#endif
//#ifdef CONFIG_ZONE_DMA32
//	 "DMA32",
//#endif
//	 "Normal",
//#ifdef CONFIG_HIGHMEM
//	 "HighMem",
//#endif
//	 "Movable",
//#ifdef CONFIG_ZONE_DEVICE
//	 "Device",
//#endif
//};

//const char * const migratetype_names[MIGRATE_TYPES] = {
//	"Unmovable",
//	"Movable",
//	"Reclaimable",
//	"HighAtomic",
//#ifdef CONFIG_CMA
//	"CMA",
//#endif
//#ifdef CONFIG_MEMORY_ISOLATION
//	"Isolate",
//#endif
//};

//compound_page_dtor * const compound_page_dtors[NR_COMPOUND_DTORS] = {
//	[NULL_COMPOUND_DTOR] = NULL,
//	[COMPOUND_PAGE_DTOR] = free_compound_page,
//#ifdef CONFIG_HUGETLB_PAGE
//	[HUGETLB_PAGE_DTOR] = free_huge_page,
//#endif
//#ifdef CONFIG_TRANSPARENT_HUGEPAGE
//	[TRANSHUGE_PAGE_DTOR] = free_transhuge_page,
//#endif
//};

//int min_free_kbytes = 1024;
//int user_min_free_kbytes = -1;
//#ifdef CONFIG_DISCONTIGMEM
///*
// * DiscontigMem defines memory ranges as separate pg_data_t even if the ranges
// * are not on separate NUMA nodes. Functionally this works but with
// * watermark_boost_factor, it can reclaim prematurely as the ranges can be
// * quite small. By default, do not boost watermarks on discontigmem as in
// * many cases very high-order allocations like THP are likely to be
// * unsupported and the premature reclaim offsets the advantage of long-term
// * fragmentation avoidance.
// */
//int watermark_boost_factor __read_mostly;
//#else
//int watermark_boost_factor __read_mostly = 15000;
//#endif
//int watermark_scale_factor = 10;

//static unsigned long nr_kernel_pages __initdata;
//static unsigned long nr_all_pages __initdata;
//static unsigned long dma_reserve __initdata;

//static unsigned long arch_zone_lowest_possible_pfn[MAX_NR_ZONES] __initdata;
//static unsigned long arch_zone_highest_possible_pfn[MAX_NR_ZONES] __initdata;
//static unsigned long required_kernelcore __initdata;
//static unsigned long required_kernelcore_percent __initdata;
//static unsigned long required_movablecore __initdata;
//static unsigned long required_movablecore_percent __initdata;
//static unsigned long zone_movable_pfn[MAX_NUMNODES] __initdata;
//static bool mirrored_kernelcore __meminitdata;

///* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
//int movable_zone;
//EXPORT_SYMBOL(movable_zone);

//#if MAX_NUMNODES > 1
//unsigned int nr_node_ids __read_mostly = MAX_NUMNODES;
//unsigned int nr_online_nodes __read_mostly = 1;
//EXPORT_SYMBOL(nr_node_ids);
//EXPORT_SYMBOL(nr_online_nodes);
//#endif

//int page_group_by_mobility_disabled __read_mostly;

//#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
///*
// * During boot we initialize deferred pages on-demand, as needed, but once
// * page_alloc_init_late() has finished, the deferred pages are all initialized,
// * and we can permanently disable that path.
// */
//static DEFINE_STATIC_KEY_TRUE(deferred_pages);

///*
// * Calling kasan_free_pages() only after deferred memory initialization
// * has completed. Poisoning pages during deferred memory init will greatly
// * lengthen the process and cause problem in large memory systems as the
// * deferred pages initialization is done with interrupt disabled.
// *
// * Assuming that there will be no reference to those newly initialized
// * pages before they are ever allocated, this should have no effect on
// * KASAN memory tracking as the poison will be properly inserted at page
// * allocation time. The only corner case is when pages are allocated by
// * on-demand allocation and then freed again before the deferred pages
// * initialization is done, but this is not likely to happen.
// */
//static inline void kasan_free_nondeferred_pages(struct page *page, int order)
//{
//	if (!static_branch_unlikely(&deferred_pages))
//		kasan_free_pages(page, order);
//}

///* Returns true if the struct page for the pfn is uninitialised */
//static inline bool __meminit early_page_uninitialised(unsigned long pfn)
//{
//	int nid = early_pfn_to_nid(pfn);

//	if (node_online(nid) && pfn >= NODE_DATA(nid)->first_deferred_pfn)
//		return true;

//	return false;
//}

///*
// * Returns true when the remaining initialisation should be deferred until
// * later in the boot cycle when it can be parallelised.
// */
//static bool __meminit
//defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
//{
//	static unsigned long prev_end_pfn, nr_initialised;

//	/*
//	 * prev_end_pfn static that contains the end of previous zone
//	 * No need to protect because called very early in boot before smp_init.
//	 */
//	if (prev_end_pfn != end_pfn) {
//		prev_end_pfn = end_pfn;
//		nr_initialised = 0;
//	}

//	/* Always populate low zones for address-constrained allocations */
//	if (end_pfn < pgdat_end_pfn(NODE_DATA(nid)))
//		return false;

//	if (NODE_DATA(nid)->first_deferred_pfn != ULONG_MAX)
//		return true;
//	/*
//	 * We start only with one section of pages, more pages are added as
//	 * needed until the rest of deferred pages are initialized.
//	 */
//	nr_initialised++;
//	if ((nr_initialised > PAGES_PER_SECTION) &&
//	    (pfn & (PAGES_PER_SECTION - 1)) == 0) {
//		NODE_DATA(nid)->first_deferred_pfn = pfn;
//		return true;
//	}
//	return false;
//}
//#else
//#define kasan_free_nondeferred_pages(p, o)	kasan_free_pages(p, o)

//static inline bool early_page_uninitialised(unsigned long pfn)
//{
//	return false;
//}

//static inline bool defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
//{
//	return false;
//}
//#endif

///* Return a pointer to the bitmap storing bits affecting a block of pages */
//static inline unsigned long *get_pageblock_bitmap(struct page *page,
//							unsigned long pfn)
//{
//#ifdef CONFIG_SPARSEMEM
//	return section_to_usemap(__pfn_to_section(pfn));
//#else
//	return page_zone(page)->pageblock_flags;
//#endif /* CONFIG_SPARSEMEM */
//}

//static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
//{
//#ifdef CONFIG_SPARSEMEM
//	pfn &= (PAGES_PER_SECTION-1);
//#else
//	pfn = pfn - round_down(page_zone(page)->zone_start_pfn, pageblock_nr_pages);
//#endif /* CONFIG_SPARSEMEM */
//	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
//}

///**
// * get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
// * @page: The page within the block of interest
// * @pfn: The target page frame number
// * @mask: mask of bits that the caller is interested in
// *
// * Return: pageblock_bits flags
// */
//static __always_inline
//unsigned long __get_pfnblock_flags_mask(struct page *page,
//					unsigned long pfn,
//					unsigned long mask)
//{
//	unsigned long *bitmap;
//	unsigned long bitidx, word_bitidx;
//	unsigned long word;

//	bitmap = get_pageblock_bitmap(page, pfn);
//	bitidx = pfn_to_bitidx(page, pfn);
//	word_bitidx = bitidx / BITS_PER_LONG;
//	bitidx &= (BITS_PER_LONG-1);

//	word = bitmap[word_bitidx];
//	return (word >> bitidx) & mask;
//}

//unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
//					unsigned long mask)
//{
//	return __get_pfnblock_flags_mask(page, pfn, mask);
//}

//static __always_inline int get_pfnblock_migratetype(struct page *page, unsigned long pfn)
//{
//	return __get_pfnblock_flags_mask(page, pfn, MIGRATETYPE_MASK);
//}

///**
// * set_pfnblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages
// * @page: The page within the block of interest
// * @flags: The flags to set
// * @pfn: The target page frame number
// * @mask: mask of bits that the caller is interested in
// */
//void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
//					unsigned long pfn,
//					unsigned long mask)
//{
//	unsigned long *bitmap;
//	unsigned long bitidx, word_bitidx;
//	unsigned long old_word, word;

//	BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
//	BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits));

//	bitmap = get_pageblock_bitmap(page, pfn);
//	bitidx = pfn_to_bitidx(page, pfn);
//	word_bitidx = bitidx / BITS_PER_LONG;
//	bitidx &= (BITS_PER_LONG-1);

//	VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);

//	mask <<= bitidx;
//	flags <<= bitidx;

//	word = READ_ONCE(bitmap[word_bitidx]);
//	for (;;) {
//		old_word = cmpxchg(&bitmap[word_bitidx], word, (word & ~mask) | flags);
//		if (word == old_word)
//			break;
//		word = old_word;
//	}
//}

//void set_pageblock_migratetype(struct page *page, int migratetype)
//{
//	if (unlikely(page_group_by_mobility_disabled &&
//		     migratetype < MIGRATE_PCPTYPES))
//		migratetype = MIGRATE_UNMOVABLE;

//	set_pfnblock_flags_mask(page, (unsigned long)migratetype,
//				page_to_pfn(page), MIGRATETYPE_MASK);
//}

//#ifdef CONFIG_DEBUG_VM
//static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
//{
//	int ret = 0;
//	unsigned seq;
//	unsigned long pfn = page_to_pfn(page);
//	unsigned long sp, start_pfn;

//	do {
//		seq = zone_span_seqbegin(zone);
//		start_pfn = zone->zone_start_pfn;
//		sp = zone->spanned_pages;
//		if (!zone_spans_pfn(zone, pfn))
//			ret = 1;
//	} while (zone_span_seqretry(zone, seq));

//	if (ret)
//		pr_err("page 0x%lx outside node %d zone %s [ 0x%lx - 0x%lx ]\n",
//			pfn, zone_to_nid(zone), zone->name,
//			start_pfn, start_pfn + sp);

//	return ret;
//}

//static int page_is_consistent(struct zone *zone, struct page *page)
//{
//	if (!pfn_valid_within(page_to_pfn(page)))
//		return 0;
//	if (zone != page_zone(page))
//		return 0;

//	return 1;
//}
///*
// * Temporary debugging check for pages not lying within a given zone.
// */
//static int __maybe_unused bad_range(struct zone *zone, struct page *page)
//{
//	if (page_outside_zone_boundaries(zone, page))
//		return 1;
//	if (!page_is_consistent(zone, page))
//		return 1;

//	return 0;
//}
//#else
//static inline int __maybe_unused bad_range(struct zone *zone, struct page *page)
//{
//	return 0;
//}
//#endif

//static void bad_page(struct page *page, const char *reason)
//{
//	static unsigned long resume;
//	static unsigned long nr_shown;
//	static unsigned long nr_unshown;

//	/*
//	 * Allow a burst of 60 reports, then keep quiet for that minute;
//	 * or allow a steady drip of one report per second.
//	 */
//	if (nr_shown == 60) {
//		if (time_before(jiffies, resume)) {
//			nr_unshown++;
//			goto out;
//		}
//		if (nr_unshown) {
//			pr_alert(
//			      "BUG: Bad page state: %lu messages suppressed\n",
//				nr_unshown);
//			nr_unshown = 0;
//		}
//		nr_shown = 0;
//	}
//	if (nr_shown++ == 0)
//		resume = jiffies + 60 * HZ;

//	pr_alert("BUG: Bad page state in process %s  pfn:%05lx\n",
//		current->comm, page_to_pfn(page));
//	__dump_page(page, reason);
//	dump_page_owner(page);

//	print_modules();
//	dump_stack();
//out:
//	/* Leave bad fields for debug, except PageBuddy could make trouble */
//	page_mapcount_reset(page); /* remove PageBuddy */
//	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
//}

///*
// * Higher-order pages are called "compound pages".  They are structured thusly:
// *
// * The first PAGE_SIZE page is called the "head page" and have PG_head set.
// *
// * The remaining PAGE_SIZE pages are called "tail pages". PageTail() is encoded
// * in bit 0 of page->compound_head. The rest of bits is pointer to head page.
// *
// * The first tail page's ->compound_dtor holds the offset in array of compound
// * page destructors. See compound_page_dtors.
// *
// * The first tail page's ->compound_order holds the order of allocation.
// * This usage means that zero-order pages may not be compound.
// */

//void free_compound_page(struct page *page)
//{
//	mem_cgroup_uncharge(page);
//	__free_pages_ok(page, compound_order(page), FPI_NONE);
//}

//void prep_compound_page(struct page *page, unsigned int order)
//{
//	int i;
//	int nr_pages = 1 << order;

//	__SetPageHead(page);
//	for (i = 1; i < nr_pages; i++) {
//		struct page *p = page + i;
//		set_page_count(p, 0);
//		p->mapping = TAIL_MAPPING;
//		set_compound_head(p, page);
//	}

//	set_compound_page_dtor(page, COMPOUND_PAGE_DTOR);
//	set_compound_order(page, order);
//	atomic_set(compound_mapcount_ptr(page), -1);
//	if (hpage_pincount_available(page))
//		atomic_set(compound_pincount_ptr(page), 0);
//}

//#ifdef CONFIG_DEBUG_PAGEALLOC
//unsigned int _debug_guardpage_minorder;

//bool _debug_pagealloc_enabled_early __read_mostly
//			= IS_ENABLED(CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT);
//EXPORT_SYMBOL(_debug_pagealloc_enabled_early);
//DEFINE_STATIC_KEY_FALSE(_debug_pagealloc_enabled);
//EXPORT_SYMBOL(_debug_pagealloc_enabled);

//DEFINE_STATIC_KEY_FALSE(_debug_guardpage_enabled);

//static int __init early_debug_pagealloc(char *buf)
//{
//	return kstrtobool(buf, &_debug_pagealloc_enabled_early);
//}
//early_param("debug_pagealloc", early_debug_pagealloc);

//void init_debug_pagealloc(void)
//{
//	if (!debug_pagealloc_enabled())
//		return;

//	static_branch_enable(&_debug_pagealloc_enabled);

//	if (!debug_guardpage_minorder())
//		return;

//	static_branch_enable(&_debug_guardpage_enabled);
//}

//static int __init debug_guardpage_minorder_setup(char *buf)
//{
//	unsigned long res;

//	if (kstrtoul(buf, 10, &res) < 0 ||  res > MAX_ORDER / 2) {
//		pr_err("Bad debug_guardpage_minorder value\n");
//		return 0;
//	}
//	_debug_guardpage_minorder = res;
//	pr_info("Setting debug_guardpage_minorder to %lu\n", res);
//	return 0;
//}
//early_param("debug_guardpage_minorder", debug_guardpage_minorder_setup);

//static inline bool set_page_guard(struct zone *zone, struct page *page,
//				unsigned int order, int migratetype)
//{
//	if (!debug_guardpage_enabled())
//		return false;

//	if (order >= debug_guardpage_minorder())
//		return false;

//	__SetPageGuard(page);
//	INIT_LIST_HEAD(&page->lru);
//	set_page_private(page, order);
//	/* Guard pages are not available for any usage */
//	__mod_zone_freepage_state(zone, -(1 << order), migratetype);

//	return true;
//}

//static inline void clear_page_guard(struct zone *zone, struct page *page,
//				unsigned int order, int migratetype)
//{
//	if (!debug_guardpage_enabled())
//		return;

//	__ClearPageGuard(page);

//	set_page_private(page, 0);
//	if (!is_migrate_isolate(migratetype))
//		__mod_zone_freepage_state(zone, (1 << order), migratetype);
//}
//#else
//static inline bool set_page_guard(struct zone *zone, struct page *page,
//			unsigned int order, int migratetype) { return false; }
//static inline void clear_page_guard(struct zone *zone, struct page *page,
//				unsigned int order, int migratetype) {}
//#endif

//static inline void set_buddy_order(struct page *page, unsigned int order)
//{
//	set_page_private(page, order);
//	__SetPageBuddy(page);
//}

///*
// * This function checks whether a page is free && is the buddy
// * we can coalesce a page and its buddy if
// * (a) the buddy is not in a hole (check before calling!) &&
// * (b) the buddy is in the buddy system &&
// * (c) a page and its buddy have the same order &&
// * (d) a page and its buddy are in the same zone.
// *
// * For recording whether a page is in the buddy system, we set PageBuddy.
// * Setting, clearing, and testing PageBuddy is serialized by zone->lock.
// *
// * For recording page's order, we use page_private(page).
// */
//static inline bool page_is_buddy(struct page *page, struct page *buddy,
//							unsigned int order)
//{
//	if (!page_is_guard(buddy) && !PageBuddy(buddy))
//		return false;

//	if (buddy_order(buddy) != order)
//		return false;

//	/*
//	 * zone check is done late to avoid uselessly calculating
//	 * zone/node ids for pages that could never merge.
//	 */
//	if (page_zone_id(page) != page_zone_id(buddy))
//		return false;

//	VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);

//	return true;
//}

//#ifdef CONFIG_COMPACTION
//static inline struct capture_control *task_capc(struct zone *zone)
//{
//	struct capture_control *capc = current->capture_control;

//	return unlikely(capc) &&
//		!(current->flags & PF_KTHREAD) &&
//		!capc->page &&
//		capc->cc->zone == zone ? capc : NULL;
//}

//static inline bool
//compaction_capture(struct capture_control *capc, struct page *page,
//		   int order, int migratetype)
//{
//	if (!capc || order != capc->cc->order)
//		return false;

//	/* Do not accidentally pollute CMA or isolated regions*/
//	if (is_migrate_cma(migratetype) ||
//	    is_migrate_isolate(migratetype))
//		return false;

//	/*
//	 * Do not let lower order allocations polluate a movable pageblock.
//	 * This might let an unmovable request use a reclaimable pageblock
//	 * and vice-versa but no more than normal fallback logic which can
//	 * have trouble finding a high-order free page.
//	 */
//	if (order < pageblock_order && migratetype == MIGRATE_MOVABLE)
//		return false;

//	capc->page = page;
//	return true;
//}

//#else
//static inline struct capture_control *task_capc(struct zone *zone)
//{
//	return NULL;
//}

//static inline bool
//compaction_capture(struct capture_control *capc, struct page *page,
//		   int order, int migratetype)
//{
//	return false;
//}
//#endif /* CONFIG_COMPACTION */

///* Used for pages not on another list */
//static inline void add_to_free_list(struct page *page, struct zone *zone,
//				    unsigned int order, int migratetype)
//{
//	struct free_area *area = &zone->free_area[order];

//	list_add(&page->lru, &area->free_list[migratetype]);
//	area->nr_free++;
//}

///* Used for pages not on another list */
//static inline void add_to_free_list_tail(struct page *page, struct zone *zone,
//					 unsigned int order, int migratetype)
//{
//	struct free_area *area = &zone->free_area[order];

//	list_add_tail(&page->lru, &area->free_list[migratetype]);
//	area->nr_free++;
//}

///*
// * Used for pages which are on another list. Move the pages to the tail
// * of the list - so the moved pages won't immediately be considered for
// * allocation again (e.g., optimization for memory onlining).
// */
//static inline void move_to_free_list(struct page *page, struct zone *zone,
//				     unsigned int order, int migratetype)
//{
//	struct free_area *area = &zone->free_area[order];

//	list_move_tail(&page->lru, &area->free_list[migratetype]);
//}

//static inline void del_page_from_free_list(struct page *page, struct zone *zone,
//					   unsigned int order)
//{
//	/* clear reported state and update reported page count */
//	if (page_reported(page))
//		__ClearPageReported(page);

//	list_del(&page->lru);
//	__ClearPageBuddy(page);
//	set_page_private(page, 0);
//	zone->free_area[order].nr_free--;
//}

///*
// * If this is not the largest possible page, check if the buddy
// * of the next-highest order is free. If it is, it's possible
// * that pages are being freed that will coalesce soon. In case,
// * that is happening, add the free page to the tail of the list
// * so it's less likely to be used soon and more likely to be merged
// * as a higher order page
// */
//static inline bool
//buddy_merge_likely(unsigned long pfn, unsigned long buddy_pfn,
//		   struct page *page, unsigned int order)
//{
//	struct page *higher_page, *higher_buddy;
//	unsigned long combined_pfn;

//	if (order >= MAX_ORDER - 2)
//		return false;

//	if (!pfn_valid_within(buddy_pfn))
//		return false;

//	combined_pfn = buddy_pfn & pfn;
//	higher_page = page + (combined_pfn - pfn);
//	buddy_pfn = __find_buddy_pfn(combined_pfn, order + 1);
//	higher_buddy = higher_page + (buddy_pfn - combined_pfn);

//	return pfn_valid_within(buddy_pfn) &&
//	       page_is_buddy(higher_page, higher_buddy, order + 1);
//}

///*
// * Freeing function for a buddy system allocator.
// *
// * The concept of a buddy system is to maintain direct-mapped table
// * (containing bit values) for memory blocks of various "orders".
// * The bottom level table contains the map for the smallest allocatable
// * units of memory (here, pages), and each level above it describes
// * pairs of units from the levels below, hence, "buddies".
// * At a high level, all that happens here is marking the table entry
// * at the bottom level available, and propagating the changes upward
// * as necessary, plus some accounting needed to play nicely with other
// * parts of the VM system.
// * At each level, we keep a list of pages, which are heads of continuous
// * free pages of length of (1 << order) and marked with PageBuddy.
// * Page's order is recorded in page_private(page) field.
// * So when we are allocating or freeing one, we can derive the state of the
// * other.  That is, if we allocate a small block, and both were
// * free, the remainder of the region must be split into blocks.
// * If a block is freed, and its buddy is also free, then this
// * triggers coalescing into a block of larger size.
// *
// * -- nyc
// */

//static inline void __free_one_page(struct page *page,
//		unsigned long pfn,
//		struct zone *zone, unsigned int order,
//		int migratetype, fpi_t fpi_flags)
//{
//	struct capture_control *capc = task_capc(zone);
//	unsigned long buddy_pfn;
//	unsigned long combined_pfn;
//	unsigned int max_order;
//	struct page *buddy;
//	bool to_tail;

//	max_order = min_t(unsigned int, MAX_ORDER, pageblock_order + 1);

//	VM_BUG_ON(!zone_is_initialized(zone));
//	VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);

//	VM_BUG_ON(migratetype == -1);
//	if (likely(!is_migrate_isolate(migratetype)))
//		__mod_zone_freepage_state(zone, 1 << order, migratetype);

//	VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);
//	VM_BUG_ON_PAGE(bad_range(zone, page), page);

//continue_merging:
//	while (order < max_order - 1) {
//		if (compaction_capture(capc, page, order, migratetype)) {
//			__mod_zone_freepage_state(zone, -(1 << order),
//								migratetype);
//			return;
//		}
//		buddy_pfn = __find_buddy_pfn(pfn, order);
//		buddy = page + (buddy_pfn - pfn);

//		if (!pfn_valid_within(buddy_pfn))
//			goto done_merging;
//		if (!page_is_buddy(page, buddy, order))
//			goto done_merging;
//		/*
//		 * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
//		 * merge with it and move up one order.
//		 */
//		if (page_is_guard(buddy))
//			clear_page_guard(zone, buddy, order, migratetype);
//		else
//			del_page_from_free_list(buddy, zone, order);
//		combined_pfn = buddy_pfn & pfn;
//		page = page + (combined_pfn - pfn);
//		pfn = combined_pfn;
//		order++;
//	}
//	if (max_order < MAX_ORDER) {
//		/* If we are here, it means order is >= pageblock_order.
//		 * We want to prevent merge between freepages on isolate
//		 * pageblock and normal pageblock. Without this, pageblock
//		 * isolation could cause incorrect freepage or CMA accounting.
//		 *
//		 * We don't want to hit this code for the more frequent
//		 * low-order merging.
//		 */
//		if (unlikely(has_isolate_pageblock(zone))) {
//			int buddy_mt;

//			buddy_pfn = __find_buddy_pfn(pfn, order);
//			buddy = page + (buddy_pfn - pfn);
//			buddy_mt = get_pageblock_migratetype(buddy);

//			if (migratetype != buddy_mt
//					&& (is_migrate_isolate(migratetype) ||
//						is_migrate_isolate(buddy_mt)))
//				goto done_merging;
//		}
//		max_order++;
//		goto continue_merging;
//	}

//done_merging:
//	set_buddy_order(page, order);

//	if (fpi_flags & FPI_TO_TAIL)
//		to_tail = true;
//	else if (is_shuffle_order(order))
//		to_tail = shuffle_pick_tail();
//	else
//		to_tail = buddy_merge_likely(pfn, buddy_pfn, page, order);

//	if (to_tail)
//		add_to_free_list_tail(page, zone, order, migratetype);
//	else
//		add_to_free_list(page, zone, order, migratetype);

//	/* Notify page reporting subsystem of freed page */
//	if (!(fpi_flags & FPI_SKIP_REPORT_NOTIFY))
//		page_reporting_notify_free(order);
//}

///*
// * A bad page could be due to a number of fields. Instead of multiple branches,
// * try and check multiple fields with one check. The caller must do a detailed
// * check if necessary.
// */
//static inline bool page_expected_state(struct page *page,
//					unsigned long check_flags)
//{
//	if (unlikely(atomic_read(&page->_mapcount) != -1))
//		return false;

//	if (unlikely((unsigned long)page->mapping |
//			page_ref_count(page) |
//#ifdef CONFIG_MEMCG
//			(unsigned long)page->mem_cgroup |
//#endif
//			(page->flags & check_flags)))
//		return false;

//	return true;
//}

//static const char *page_bad_reason(struct page *page, unsigned long flags)
//{
//	const char *bad_reason = NULL;

//	if (unlikely(atomic_read(&page->_mapcount) != -1))
//		bad_reason = "nonzero mapcount";
//	if (unlikely(page->mapping != NULL))
//		bad_reason = "non-NULL mapping";
//	if (unlikely(page_ref_count(page) != 0))
//		bad_reason = "nonzero _refcount";
//	if (unlikely(page->flags & flags)) {
//		if (flags == PAGE_FLAGS_CHECK_AT_PREP)
//			bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag(s) set";
//		else
//			bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
//	}
//#ifdef CONFIG_MEMCG
//	if (unlikely(page->mem_cgroup))
//		bad_reason = "page still charged to cgroup";
//#endif
//	return bad_reason;
//}

//static void check_free_page_bad(struct page *page)
//{
//	bad_page(page,
//		 page_bad_reason(page, PAGE_FLAGS_CHECK_AT_FREE));
//}

//static inline int check_free_page(struct page *page)
//{
//	if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_FREE)))
//		return 0;

//	/* Something has gone sideways, find it */
//	check_free_page_bad(page);
//	return 1;
//}

//static int free_tail_pages_check(struct page *head_page, struct page *page)
//{
//	int ret = 1;

//	/*
//	 * We rely page->lru.next never has bit 0 set, unless the page
//	 * is PageTail(). Let's make sure that's true even for poisoned ->lru.
//	 */
//	BUILD_BUG_ON((unsigned long)LIST_POISON1 & 1);

//	if (!IS_ENABLED(CONFIG_DEBUG_VM)) {
//		ret = 0;
//		goto out;
//	}
//	switch (page - head_page) {
//	case 1:
//		/* the first tail page: ->mapping may be compound_mapcount() */
//		if (unlikely(compound_mapcount(page))) {
//			bad_page(page, "nonzero compound_mapcount");
//			goto out;
//		}
//		break;
//	case 2:
//		/*
//		 * the second tail page: ->mapping is
//		 * deferred_list.next -- ignore value.
//		 */
//		break;
//	default:
//		if (page->mapping != TAIL_MAPPING) {
//			bad_page(page, "corrupted mapping in tail page");
//			goto out;
//		}
//		break;
//	}
//	if (unlikely(!PageTail(page))) {
//		bad_page(page, "PageTail not set");
//		goto out;
//	}
//	if (unlikely(compound_head(page) != head_page)) {
//		bad_page(page, "compound_head not consistent");
//		goto out;
//	}
//	ret = 0;
//out:
//	page->mapping = NULL;
//	clear_compound_head(page);
//	return ret;
//}

//static void kernel_init_free_pages(struct page *page, int numpages)
//{
//	int i;

//	/* s390's use of memset() could override KASAN redzones. */
//	kasan_disable_current();
//	for (i = 0; i < numpages; i++)
//		clear_highpage(page + i);
//	kasan_enable_current();
//}

//static __always_inline bool free_pages_prepare(struct page *page,
//					unsigned int order, bool check_free)
//{
//	int bad = 0;

//	VM_BUG_ON_PAGE(PageTail(page), page);

//	trace_mm_page_free(page, order);

//	if (unlikely(PageHWPoison(page)) && !order) {
//		/*
//		 * Do not let hwpoison pages hit pcplists/buddy
//		 * Untie memcg state and reset page's owner
//		 */
//		if (memcg_kmem_enabled() && PageKmemcg(page))
//			__memcg_kmem_uncharge_page(page, order);
//		reset_page_owner(page, order);
//		return false;
//	}

//	/*
//	 * Check tail pages before head page information is cleared to
//	 * avoid checking PageCompound for order-0 pages.
//	 */
//	if (unlikely(order)) {
//		bool compound = PageCompound(page);
//		int i;

//		VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);

//		if (compound)
//			ClearPageDoubleMap(page);
//		for (i = 1; i < (1 << order); i++) {
//			if (compound)
//				bad += free_tail_pages_check(page, page + i);
//			if (unlikely(check_free_page(page + i))) {
//				bad++;
//				continue;
//			}
//			(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
//		}
//	}
//	if (PageMappingFlags(page))
//		page->mapping = NULL;
//	if (memcg_kmem_enabled() && PageKmemcg(page))
//		__memcg_kmem_uncharge_page(page, order);
//	if (check_free)
//		bad += check_free_page(page);
//	if (bad)
//		return false;

//	page_cpupid_reset_last(page);
//	page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
//	reset_page_owner(page, order);

//	if (!PageHighMem(page)) {
//		debug_check_no_locks_freed(page_address(page),
//					   PAGE_SIZE << order);
//		debug_check_no_obj_freed(page_address(page),
//					   PAGE_SIZE << order);
//	}
//	if (want_init_on_free())
//		kernel_init_free_pages(page, 1 << order);

//	kernel_poison_pages(page, 1 << order, 0);
//	/*
//	 * arch_free_page() can make the page's contents inaccessible.  s390
//	 * does this.  So nothing which can access the page's contents should
//	 * happen after this.
//	 */
//	arch_free_page(page, order);

//	if (debug_pagealloc_enabled_static())
//		kernel_map_pages(page, 1 << order, 0);

//	kasan_free_nondeferred_pages(page, order);

//	return true;
//}

//#ifdef CONFIG_DEBUG_VM
///*
// * With DEBUG_VM enabled, order-0 pages are checked immediately when being freed
// * to pcp lists. With debug_pagealloc also enabled, they are also rechecked when
// * moved from pcp lists to free lists.
// */
//static bool free_pcp_prepare(struct page *page)
//{
//	return free_pages_prepare(page, 0, true);
//}

//static bool bulkfree_pcp_prepare(struct page *page)
//{
//	if (debug_pagealloc_enabled_static())
//		return check_free_page(page);
//	else
//		return false;
//}
//#else
///*
// * With DEBUG_VM disabled, order-0 pages being freed are checked only when
// * moving from pcp lists to free list in order to reduce overhead. With
// * debug_pagealloc enabled, they are checked also immediately when being freed
// * to the pcp lists.
// */
//static bool free_pcp_prepare(struct page *page)
//{
//	if (debug_pagealloc_enabled_static())
//		return free_pages_prepare(page, 0, true);
//	else
//		return free_pages_prepare(page, 0, false);
//}

//static bool bulkfree_pcp_prepare(struct page *page)
//{
//	return check_free_page(page);
//}
//#endif /* CONFIG_DEBUG_VM */

//static inline void prefetch_buddy(struct page *page)
//{
//	unsigned long pfn = page_to_pfn(page);
//	unsigned long buddy_pfn = __find_buddy_pfn(pfn, 0);
//	struct page *buddy = page + (buddy_pfn - pfn);

//	prefetch(buddy);
//}

///*
// * Frees a number of pages from the PCP lists
// * Assumes all pages on list are in same zone, and of same order.
// * count is the number of pages to free.
// *
// * If the zone was previously in an "all pages pinned" state then look to
// * see if this freeing clears that state.
// *
// * And clear the zone's pages_scanned counter, to hold off the "all pages are
// * pinned" detection logic.
// */
//static void free_pcppages_bulk(struct zone *zone, int count,
//					struct per_cpu_pages *pcp)
//{
//	int migratetype = 0;
//	int batch_free = 0;
//	int prefetch_nr = 0;
//	bool isolated_pageblocks;
//	struct page *page, *tmp;
//	LIST_HEAD(head);

//	/*
//	 * Ensure proper count is passed which otherwise would stuck in the
//	 * below while (list_empty(list)) loop.
//	 */
//	count = min(pcp->count, count);
//	while (count) {
//		struct list_head *list;

//		/*
//		 * Remove pages from lists in a round-robin fashion. A
//		 * batch_free count is maintained that is incremented when an
//		 * empty list is encountered.  This is so more pages are freed
//		 * off fuller lists instead of spinning excessively around empty
//		 * lists
//		 */
//		do {
//			batch_free++;
//			if (++migratetype == MIGRATE_PCPTYPES)
//				migratetype = 0;
//			list = &pcp->lists[migratetype];
//		} while (list_empty(list));

//		/* This is the only non-empty list. Free them all. */
//		if (batch_free == MIGRATE_PCPTYPES)
//			batch_free = count;

//		do {
//			page = list_last_entry(list, struct page, lru);
//			/* must delete to avoid corrupting pcp list */
//			list_del(&page->lru);
//			pcp->count--;

//			if (bulkfree_pcp_prepare(page))
//				continue;

//			list_add_tail(&page->lru, &head);

//			/*
//			 * We are going to put the page back to the global
//			 * pool, prefetch its buddy to speed up later access
//			 * under zone->lock. It is believed the overhead of
//			 * an additional test and calculating buddy_pfn here
//			 * can be offset by reduced memory latency later. To
//			 * avoid excessive prefetching due to large count, only
//			 * prefetch buddy for the first pcp->batch nr of pages.
//			 */
//			if (prefetch_nr++ < pcp->batch)
//				prefetch_buddy(page);
//		} while (--count && --batch_free && !list_empty(list));
//	}

//	spin_lock(&zone->lock);
//	isolated_pageblocks = has_isolate_pageblock(zone);

//	/*
//	 * Use safe version since after __free_one_page(),
//	 * page->lru.next will not point to original list.
//	 */
//	list_for_each_entry_safe(page, tmp, &head, lru) {
//		int mt = get_pcppage_migratetype(page);
//		/* MIGRATE_ISOLATE page should not go to pcplists */
//		VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
//		/* Pageblock could have been isolated meanwhile */
//		if (unlikely(isolated_pageblocks))
//			mt = get_pageblock_migratetype(page);

//		__free_one_page(page, page_to_pfn(page), zone, 0, mt, FPI_NONE);
//		trace_mm_page_pcpu_drain(page, 0, mt);
//	}
//	spin_unlock(&zone->lock);
//}

//static void free_one_page(struct zone *zone,
//				struct page *page, unsigned long pfn,
//				unsigned int order,
//				int migratetype, fpi_t fpi_flags)
//{
//	spin_lock(&zone->lock);
//	if (unlikely(has_isolate_pageblock(zone) ||
//		is_migrate_isolate(migratetype))) {
//		migratetype = get_pfnblock_migratetype(page, pfn);
//	}
//	__free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
//	spin_unlock(&zone->lock);
//}

//static void __meminit __init_single_page(struct page *page, unsigned long pfn,
//				unsigned long zone, int nid)
//{
//	mm_zero_struct_page(page);
//	set_page_links(page, zone, nid, pfn);
//	init_page_count(page);
//	page_mapcount_reset(page);
//	page_cpupid_reset_last(page);
//	page_kasan_tag_reset(page);

//	INIT_LIST_HEAD(&page->lru);
//#ifdef WANT_PAGE_VIRTUAL
//	/* The shift won't overflow because ZONE_NORMAL is below 4G. */
//	if (!is_highmem_idx(zone))
//		set_page_address(page, __va(pfn << PAGE_SHIFT));
//#endif
//}

//#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
//static void __meminit init_reserved_page(unsigned long pfn)
//{
//	pg_data_t *pgdat;
//	int nid, zid;

//	if (!early_page_uninitialised(pfn))
//		return;

//	nid = early_pfn_to_nid(pfn);
//	pgdat = NODE_DATA(nid);

//	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
//		struct zone *zone = &pgdat->node_zones[zid];

//		if (pfn >= zone->zone_start_pfn && pfn < zone_end_pfn(zone))
//			break;
//	}
//	__init_single_page(pfn_to_page(pfn), pfn, zid, nid);
//}
//#else
//static inline void init_reserved_page(unsigned long pfn)
//{
//}
//#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */

///*
// * Initialised pages do not have PageReserved set. This function is
// * called for each range allocated by the bootmem allocator and
// * marks the pages PageReserved. The remaining valid pages are later
// * sent to the buddy page allocator.
// */
//void __meminit reserve_bootmem_region(phys_addr_t start, phys_addr_t end)
//{
//	unsigned long start_pfn = PFN_DOWN(start);
//	unsigned long end_pfn = PFN_UP(end);

//	for (; start_pfn < end_pfn; start_pfn++) {
//		if (pfn_valid(start_pfn)) {
//			struct page *page = pfn_to_page(start_pfn);

//			init_reserved_page(start_pfn);

//			/* Avoid false-positive PageTail() */
//			INIT_LIST_HEAD(&page->lru);

//			/*
//			 * no need for atomic set_bit because the struct
//			 * page is not visible yet so nobody should
//			 * access it yet.
//			 */
//			__SetPageReserved(page);
//		}
//	}
//}

//static void __free_pages_ok(struct page *page, unsigned int order,
//			    fpi_t fpi_flags)
//{
//	unsigned long flags;
//	int migratetype;
//	unsigned long pfn = page_to_pfn(page);

//	if (!free_pages_prepare(page, order, true))
//		return;

//	migratetype = get_pfnblock_migratetype(page, pfn);
//	local_irq_save(flags);
//	__count_vm_events(PGFREE, 1 << order);
//	free_one_page(page_zone(page), page, pfn, order, migratetype,
//		      fpi_flags);
//	local_irq_restore(flags);
//}

//void __free_pages_core(struct page *page, unsigned int order)
//{
//	unsigned int nr_pages = 1 << order;
//	struct page *p = page;
//	unsigned int loop;

//	/*
//	 * When initializing the memmap, __init_single_page() sets the refcount
//	 * of all pages to 1 ("allocated"/"not free"). We have to set the
//	 * refcount of all involved pages to 0.
//	 */
//	prefetchw(p);
//	for (loop = 0; loop < (nr_pages - 1); loop++, p++) {
//		prefetchw(p + 1);
//		__ClearPageReserved(p);
//		set_page_count(p, 0);
//	}
//	__ClearPageReserved(p);
//	set_page_count(p, 0);

//	atomic_long_add(nr_pages, &page_zone(page)->managed_pages);

//	/*
//	 * Bypass PCP and place fresh pages right to the tail, primarily
//	 * relevant for memory onlining.
//	 */
//	__free_pages_ok(page, order, FPI_TO_TAIL);
//}

//#ifdef CONFIG_NEED_MULTIPLE_NODES

//static struct mminit_pfnnid_cache early_pfnnid_cache __meminitdata;

//#ifndef CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID

///*
// * Required by SPARSEMEM. Given a PFN, return what node the PFN is on.
// */
//int __meminit __early_pfn_to_nid(unsigned long pfn,
//					struct mminit_pfnnid_cache *state)
//{
//	unsigned long start_pfn, end_pfn;
//	int nid;

//	if (state->last_start <= pfn && pfn < state->last_end)
//		return state->last_nid;

//	nid = memblock_search_pfn_nid(pfn, &start_pfn, &end_pfn);
//	if (nid != NUMA_NO_NODE) {
//		state->last_start = start_pfn;
//		state->last_end = end_pfn;
//		state->last_nid = nid;
//	}

//	return nid;
//}
//#endif /* CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID */

//int __meminit early_pfn_to_nid(unsigned long pfn)
//{
//	static DEFINE_SPINLOCK(early_pfn_lock);
//	int nid;

//	spin_lock(&early_pfn_lock);
//	nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
//	if (nid < 0)
//		nid = first_online_node;
//	spin_unlock(&early_pfn_lock);

//	return nid;
//}
//#endif /* CONFIG_NEED_MULTIPLE_NODES */

//void __init memblock_free_pages(struct page *page, unsigned long pfn,
//							unsigned int order)
//{
//	if (early_page_uninitialised(pfn))
//		return;
//	__free_pages_core(page, order);
//}

///*
// * Check that the whole (or subset of) a pageblock given by the interval of
// * [start_pfn, end_pfn) is valid and within the same zone, before scanning it
// * with the migration of free compaction scanner. The scanners then need to
// * use only pfn_valid_within() check for arches that allow holes within
// * pageblocks.
// *
// * Return struct page pointer of start_pfn, or NULL if checks were not passed.
// *
// * It's possible on some configurations to have a setup like node0 node1 node0
// * i.e. it's possible that all pages within a zones range of pages do not
// * belong to a single zone. We assume that a border between node0 and node1
// * can occur within a single pageblock, but not a node0 node1 node0
// * interleaving within a single pageblock. It is therefore sufficient to check
// * the first and last page of a pageblock and avoid checking each individual
// * page in a pageblock.
// */
//struct page *__pageblock_pfn_to_page(unsigned long start_pfn,
//				     unsigned long end_pfn, struct zone *zone)
//{
//	struct page *start_page;
//	struct page *end_page;

//	/* end_pfn is one past the range we are checking */
//	end_pfn--;

//	if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn))
//		return NULL;

//	start_page = pfn_to_online_page(start_pfn);
//	if (!start_page)
//		return NULL;

//	if (page_zone(start_page) != zone)
//		return NULL;

//	end_page = pfn_to_page(end_pfn);

//	/* This gives a shorter code than deriving page_zone(end_page) */
//	if (page_zone_id(start_page) != page_zone_id(end_page))
//		return NULL;

//	return start_page;
//}

//void set_zone_contiguous(struct zone *zone)
//{
//	unsigned long block_start_pfn = zone->zone_start_pfn;
//	unsigned long block_end_pfn;

//	block_end_pfn = ALIGN(block_start_pfn + 1, pageblock_nr_pages);
//	for (; block_start_pfn < zone_end_pfn(zone);
//			block_start_pfn = block_end_pfn,
//			 block_end_pfn += pageblock_nr_pages) {

//		block_end_pfn = min(block_end_pfn, zone_end_pfn(zone));

//		if (!__pageblock_pfn_to_page(block_start_pfn,
//					     block_end_pfn, zone))
//			return;
//		cond_resched();
//	}

//	/* We confirm that there is no hole */
//	zone->contiguous = true;
//}

//void clear_zone_contiguous(struct zone *zone)
//{
//	zone->contiguous = false;
//}

//#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
//static void __init deferred_free_range(unsigned long pfn,
//				       unsigned long nr_pages)
//{
//	struct page *page;
//	unsigned long i;

//	if (!nr_pages)
//		return;

//	page = pfn_to_page(pfn);

//	/* Free a large naturally-aligned chunk if possible */
//	if (nr_pages == pageblock_nr_pages &&
//	    (pfn & (pageblock_nr_pages - 1)) == 0) {
//		set_pageblock_migratetype(page, MIGRATE_MOVABLE);
//		__free_pages_core(page, pageblock_order);
//		return;
//	}

//	for (i = 0; i < nr_pages; i++, page++, pfn++) {
//		if ((pfn & (pageblock_nr_pages - 1)) == 0)
//			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
//		__free_pages_core(page, 0);
//	}
//}

///* Completion tracking for deferred_init_memmap() threads */
//static atomic_t pgdat_init_n_undone __initdata;
//static __initdata DECLARE_COMPLETION(pgdat_init_all_done_comp);

//static inline void __init pgdat_init_report_one_done(void)
//{
//	if (atomic_dec_and_test(&pgdat_init_n_undone))
//		complete(&pgdat_init_all_done_comp);
//}

///*
// * Returns true if page needs to be initialized or freed to buddy allocator.
// *
// * First we check if pfn is valid on architectures where it is possible to have
// * holes within pageblock_nr_pages. On systems where it is not possible, this
// * function is optimized out.
// *
// * Then, we check if a current large page is valid by only checking the validity
// * of the head pfn.
// */
//static inline bool __init deferred_pfn_valid(unsigned long pfn)
//{
//	if (!pfn_valid_within(pfn))
//		return false;
//	if (!(pfn & (pageblock_nr_pages - 1)) && !pfn_valid(pfn))
//		return false;
//	return true;
//}

///*
// * Free pages to buddy allocator. Try to free aligned pages in
// * pageblock_nr_pages sizes.
// */
//static void __init deferred_free_pages(unsigned long pfn,
//				       unsigned long end_pfn)
//{
//	unsigned long nr_pgmask = pageblock_nr_pages - 1;
//	unsigned long nr_free = 0;

//	for (; pfn < end_pfn; pfn++) {
//		if (!deferred_pfn_valid(pfn)) {
//			deferred_free_range(pfn - nr_free, nr_free);
//			nr_free = 0;
//		} else if (!(pfn & nr_pgmask)) {
//			deferred_free_range(pfn - nr_free, nr_free);
//			nr_free = 1;
//		} else {
//			nr_free++;
//		}
//	}
//	/* Free the last block of pages to allocator */
//	deferred_free_range(pfn - nr_free, nr_free);
//}

///*
// * Initialize struct pages.  We minimize pfn page lookups and scheduler checks
// * by performing it only once every pageblock_nr_pages.
// * Return number of pages initialized.
// */
//static unsigned long  __init deferred_init_pages(struct zone *zone,
//						 unsigned long pfn,
//						 unsigned long end_pfn)
//{
//	unsigned long nr_pgmask = pageblock_nr_pages - 1;
//	int nid = zone_to_nid(zone);
//	unsigned long nr_pages = 0;
//	int zid = zone_idx(zone);
//	struct page *page = NULL;

//	for (; pfn < end_pfn; pfn++) {
//		if (!deferred_pfn_valid(pfn)) {
//			page = NULL;
//			continue;
//		} else if (!page || !(pfn & nr_pgmask)) {
//			page = pfn_to_page(pfn);
//		} else {
//			page++;
//		}
//		__init_single_page(page, pfn, zid, nid);
//		nr_pages++;
//	}
//	return (nr_pages);
//}

///*
// * This function is meant to pre-load the iterator for the zone init.
// * Specifically it walks through the ranges until we are caught up to the
// * first_init_pfn value and exits there. If we never encounter the value we
// * return false indicating there are no valid ranges left.
// */
//static bool __init
//deferred_init_mem_pfn_range_in_zone(u64 *i, struct zone *zone,
//				    unsigned long *spfn, unsigned long *epfn,
//				    unsigned long first_init_pfn)
//{
//	u64 j;

//	/*
//	 * Start out by walking through the ranges in this zone that have
//	 * already been initialized. We don't need to do anything with them
//	 * so we just need to flush them out of the system.
//	 */
//	for_each_free_mem_pfn_range_in_zone(j, zone, spfn, epfn) {
//		if (*epfn <= first_init_pfn)
//			continue;
//		if (*spfn < first_init_pfn)
//			*spfn = first_init_pfn;
//		*i = j;
//		return true;
//	}

//	return false;
//}

///*
// * Initialize and free pages. We do it in two loops: first we initialize
// * struct page, then free to buddy allocator, because while we are
// * freeing pages we can access pages that are ahead (computing buddy
// * page in __free_one_page()).
// *
// * In order to try and keep some memory in the cache we have the loop
// * broken along max page order boundaries. This way we will not cause
// * any issues with the buddy page computation.
// */
//static unsigned long __init
//deferred_init_maxorder(u64 *i, struct zone *zone, unsigned long *start_pfn,
//		       unsigned long *end_pfn)
//{
//	unsigned long mo_pfn = ALIGN(*start_pfn + 1, MAX_ORDER_NR_PAGES);
//	unsigned long spfn = *start_pfn, epfn = *end_pfn;
//	unsigned long nr_pages = 0;
//	u64 j = *i;

//	/* First we loop through and initialize the page values */
//	for_each_free_mem_pfn_range_in_zone_from(j, zone, start_pfn, end_pfn) {
//		unsigned long t;

//		if (mo_pfn <= *start_pfn)
//			break;

//		t = min(mo_pfn, *end_pfn);
//		nr_pages += deferred_init_pages(zone, *start_pfn, t);

//		if (mo_pfn < *end_pfn) {
//			*start_pfn = mo_pfn;
//			break;
//		}
//	}

//	/* Reset values and now loop through freeing pages as needed */
//	swap(j, *i);

//	for_each_free_mem_pfn_range_in_zone_from(j, zone, &spfn, &epfn) {
//		unsigned long t;

//		if (mo_pfn <= spfn)
//			break;

//		t = min(mo_pfn, epfn);
//		deferred_free_pages(spfn, t);

//		if (mo_pfn <= epfn)
//			break;
//	}

//	return nr_pages;
//}

//static void __init
//deferred_init_memmap_chunk(unsigned long start_pfn, unsigned long end_pfn,
//			   void *arg)
//{
//	unsigned long spfn, epfn;
//	struct zone *zone = arg;
//	u64 i;

//	deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, start_pfn);

//	/*
//	 * Initialize and free pages in MAX_ORDER sized increments so that we
//	 * can avoid introducing any issues with the buddy allocator.
//	 */
//	while (spfn < end_pfn) {
//		deferred_init_maxorder(&i, zone, &spfn, &epfn);
//		cond_resched();
//	}
//}

///* An arch may override for more concurrency. */
//__weak int __init
//deferred_page_init_max_threads(const struct cpumask *node_cpumask)
//{
//	return 1;
//}

///* Initialise remaining memory on a node */
//static int __init deferred_init_memmap(void *data)
//{
//	pg_data_t *pgdat = data;
//	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
//	unsigned long spfn = 0, epfn = 0;
//	unsigned long first_init_pfn, flags;
//	unsigned long start = jiffies;
//	struct zone *zone;
//	int zid, max_threads;
//	u64 i;

//	/* Bind memory initialisation thread to a local node if possible */
//	if (!cpumask_empty(cpumask))
//		set_cpus_allowed_ptr(current, cpumask);

//	pgdat_resize_lock(pgdat, &flags);
//	first_init_pfn = pgdat->first_deferred_pfn;
//	if (first_init_pfn == ULONG_MAX) {
//		pgdat_resize_unlock(pgdat, &flags);
//		pgdat_init_report_one_done();
//		return 0;
//	}

//	/* Sanity check boundaries */
//	BUG_ON(pgdat->first_deferred_pfn < pgdat->node_start_pfn);
//	BUG_ON(pgdat->first_deferred_pfn > pgdat_end_pfn(pgdat));
//	pgdat->first_deferred_pfn = ULONG_MAX;

//	/*
//	 * Once we unlock here, the zone cannot be grown anymore, thus if an
//	 * interrupt thread must allocate this early in boot, zone must be
//	 * pre-grown prior to start of deferred page initialization.
//	 */
//	pgdat_resize_unlock(pgdat, &flags);

//	/* Only the highest zone is deferred so find it */
//	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
//		zone = pgdat->node_zones + zid;
//		if (first_init_pfn < zone_end_pfn(zone))
//			break;
//	}

//	/* If the zone is empty somebody else may have cleared out the zone */
//	if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
//						 first_init_pfn))
//		goto zone_empty;

//	max_threads = deferred_page_init_max_threads(cpumask);

//	while (spfn < epfn) {
//		unsigned long epfn_align = ALIGN(epfn, PAGES_PER_SECTION);
//		struct padata_mt_job job = {
//			.thread_fn   = deferred_init_memmap_chunk,
//			.fn_arg      = zone,
//			.start       = spfn,
//			.size        = epfn_align - spfn,
//			.align       = PAGES_PER_SECTION,
//			.min_chunk   = PAGES_PER_SECTION,
//			.max_threads = max_threads,
//		};

//		padata_do_multithreaded(&job);
//		deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
//						    epfn_align);
//	}
//zone_empty:
//	/* Sanity check that the next zone really is unpopulated */
//	WARN_ON(++zid < MAX_NR_ZONES && populated_zone(++zone));

//	pr_info("node %d deferred pages initialised in %ums\n",
//		pgdat->node_id, jiffies_to_msecs(jiffies - start));

//	pgdat_init_report_one_done();
//	return 0;
//}

///*
// * If this zone has deferred pages, try to grow it by initializing enough
// * deferred pages to satisfy the allocation specified by order, rounded up to
// * the nearest PAGES_PER_SECTION boundary.  So we're adding memory in increments
// * of SECTION_SIZE bytes by initializing struct pages in increments of
// * PAGES_PER_SECTION * sizeof(struct page) bytes.
// *
// * Return true when zone was grown, otherwise return false. We return true even
// * when we grow less than requested, to let the caller decide if there are
// * enough pages to satisfy the allocation.
// *
// * Note: We use noinline because this function is needed only during boot, and
// * it is called from a __ref function _deferred_grow_zone. This way we are
// * making sure that it is not inlined into permanent text section.
// */
//static noinline bool __init
//deferred_grow_zone(struct zone *zone, unsigned int order)
//{
//	unsigned long nr_pages_needed = ALIGN(1 << order, PAGES_PER_SECTION);
//	pg_data_t *pgdat = zone->zone_pgdat;
//	unsigned long first_deferred_pfn = pgdat->first_deferred_pfn;
//	unsigned long spfn, epfn, flags;
//	unsigned long nr_pages = 0;
//	u64 i;

//	/* Only the last zone may have deferred pages */
//	if (zone_end_pfn(zone) != pgdat_end_pfn(pgdat))
//		return false;

//	pgdat_resize_lock(pgdat, &flags);

//	/*
//	 * If someone grew this zone while we were waiting for spinlock, return
//	 * true, as there might be enough pages already.
//	 */
//	if (first_deferred_pfn != pgdat->first_deferred_pfn) {
//		pgdat_resize_unlock(pgdat, &flags);
//		return true;
//	}

//	/* If the zone is empty somebody else may have cleared out the zone */
//	if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
//						 first_deferred_pfn)) {
//		pgdat->first_deferred_pfn = ULONG_MAX;
//		pgdat_resize_unlock(pgdat, &flags);
//		/* Retry only once. */
//		return first_deferred_pfn != ULONG_MAX;
//	}

//	/*
//	 * Initialize and free pages in MAX_ORDER sized increments so
//	 * that we can avoid introducing any issues with the buddy
//	 * allocator.
//	 */
//	while (spfn < epfn) {
//		/* update our first deferred PFN for this section */
//		first_deferred_pfn = spfn;

//		nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn);
//		touch_nmi_watchdog();

//		/* We should only stop along section boundaries */
//		if ((first_deferred_pfn ^ spfn) < PAGES_PER_SECTION)
//			continue;

//		/* If our quota has been met we can stop here */
//		if (nr_pages >= nr_pages_needed)
//			break;
//	}

//	pgdat->first_deferred_pfn = spfn;
//	pgdat_resize_unlock(pgdat, &flags);

//	return nr_pages > 0;
//}

///*
// * deferred_grow_zone() is __init, but it is called from
// * get_page_from_freelist() during early boot until deferred_pages permanently
// * disables this call. This is why we have refdata wrapper to avoid warning,
// * and to ensure that the function body gets unloaded.
// */
//static bool __ref
//_deferred_grow_zone(struct zone *zone, unsigned int order)
//{
//	return deferred_grow_zone(zone, order);
//}

//#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */

//void __init page_alloc_init_late(void)
//{
//	struct zone *zone;
//	int nid;

//#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT

//	/* There will be num_node_state(N_MEMORY) threads */
//	atomic_set(&pgdat_init_n_undone, num_node_state(N_MEMORY));
//	for_each_node_state(nid, N_MEMORY) {
//		kthread_run(deferred_init_memmap, NODE_DATA(nid), "pgdatinit%d", nid);
//	}

//	/* Block until all are initialised */
//	wait_for_completion(&pgdat_init_all_done_comp);

//	/*
//	 * The number of managed pages has changed due to the initialisation
//	 * so the pcpu batch and high limits needs to be updated or the limits
//	 * will be artificially small.
//	 */
//	for_each_populated_zone(zone)
//		zone_pcp_update(zone);

//	/*
//	 * We initialized the rest of the deferred pages.  Permanently disable
//	 * on-demand struct page initialization.
//	 */
//	static_branch_disable(&deferred_pages);

//	/* Reinit limits that are based on free pages after the kernel is up */
//	files_maxfiles_init();
//#endif

//	/* Discard memblock private memory */
//	memblock_discard();

//	for_each_node_state(nid, N_MEMORY)
//		shuffle_free_memory(NODE_DATA(nid));

//	for_each_populated_zone(zone)
//		set_zone_contiguous(zone);
//}

//#ifdef CONFIG_CMA
///* Free whole pageblock and set its migration type to MIGRATE_CMA. */
//void __init init_cma_reserved_pageblock(struct page *page)
//{
//	unsigned i = pageblock_nr_pages;
//	struct page *p = page;

//	do {
//		__ClearPageReserved(p);
//		set_page_count(p, 0);
//	} while (++p, --i);

//	set_pageblock_migratetype(page, MIGRATE_CMA);

//	if (pageblock_order >= MAX_ORDER) {
//		i = pageblock_nr_pages;
//		p = page;
//		do {
//			set_page_refcounted(p);
//			__free_pages(p, MAX_ORDER - 1);
//			p += MAX_ORDER_NR_PAGES;
//		} while (i -= MAX_ORDER_NR_PAGES);
//	} else {
//		set_page_refcounted(page);
//		__free_pages(page, pageblock_order);
//	}

//	adjust_managed_page_count(page, pageblock_nr_pages);
//}
//#endif

///*
// * The order of subdivision here is critical for the IO subsystem.
// * Please do not alter this order without good reasons and regression
// * testing. Specifically, as large blocks of memory are subdivided,
// * the order in which smaller blocks are delivered depends on the order
// * they're subdivided in this function. This is the primary factor
// * influencing the order in which pages are delivered to the IO
// * subsystem according to empirical testing, and this is also justified
// * by considering the behavior of a buddy system containing a single
// * large block of memory acted on by a series of small allocations.
// * This behavior is a critical factor in sglist merging's success.
// *
// * -- nyc
// */
//static inline void expand(struct zone *zone, struct page *page,
//	int low, int high, int migratetype)
//{
//	unsigned long size = 1 << high;

//	while (high > low) {
//		high--;
//		size >>= 1;
//		VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);

//		/*
//		 * Mark as guard pages (or page), that will allow to
//		 * merge back to allocator when buddy will be freed.
//		 * Corresponding page table entries will not be touched,
//		 * pages will stay not present in virtual address space
//		 */
//		if (set_page_guard(zone, &page[size], high, migratetype))
//			continue;

//		add_to_free_list(&page[size], zone, high, migratetype);
//		set_buddy_order(&page[size], high);
//	}
//}

//static void check_new_page_bad(struct page *page)
//{
//	if (unlikely(page->flags & __PG_HWPOISON)) {
//		/* Don't complain about hwpoisoned pages */
//		page_mapcount_reset(page); /* remove PageBuddy */
//		return;
//	}

//	bad_page(page,
//		 page_bad_reason(page, PAGE_FLAGS_CHECK_AT_PREP));
//}

///*
// * This page is about to be returned from the page allocator
// */
//static inline int check_new_page(struct page *page)
//{
//	if (likely(page_expected_state(page,
//				PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON)))
//		return 0;

//	check_new_page_bad(page);
//	return 1;
//}

//static inline bool free_pages_prezeroed(void)
//{
//	return (IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) &&
//		page_poisoning_enabled()) || want_init_on_free();
//}

//#ifdef CONFIG_DEBUG_VM
///*
// * With DEBUG_VM enabled, order-0 pages are checked for expected state when
// * being allocated from pcp lists. With debug_pagealloc also enabled, they are
// * also checked when pcp lists are refilled from the free lists.
// */
//static inline bool check_pcp_refill(struct page *page)
//{
//	if (debug_pagealloc_enabled_static())
//		return check_new_page(page);
//	else
//		return false;
//}

//static inline bool check_new_pcp(struct page *page)
//{
//	return check_new_page(page);
//}
//#else
///*
// * With DEBUG_VM disabled, free order-0 pages are checked for expected state
// * when pcp lists are being refilled from the free lists. With debug_pagealloc
// * enabled, they are also checked when being allocated from the pcp lists.
// */
//static inline bool check_pcp_refill(struct page *page)
//{
//	return check_new_page(page);
//}
//static inline bool check_new_pcp(struct page *page)
//{
//	if (debug_pagealloc_enabled_static())
//		return check_new_page(page);
//	else
//		return false;
//}
//#endif /* CONFIG_DEBUG_VM */

//static bool check_new_pages(struct page *page, unsigned int order)
//{
//	int i;
//	for (i = 0; i < (1 << order); i++) {
//		struct page *p = page + i;

//		if (unlikely(check_new_page(p)))
//			return true;
//	}

//	return false;
//}

//inline void post_alloc_hook(struct page *page, unsigned int order,
//				gfp_t gfp_flags)
//{
//	set_page_private(page, 0);
//	set_page_refcounted(page);

//	arch_alloc_page(page, order);
//	if (debug_pagealloc_enabled_static())
//		kernel_map_pages(page, 1 << order, 1);
//	kasan_alloc_pages(page, order);
//	kernel_poison_pages(page, 1 << order, 1);
//	set_page_owner(page, order, gfp_flags);
//}

//static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
//							unsigned int alloc_flags)
//{
//	post_alloc_hook(page, order, gfp_flags);

//	if (!free_pages_prezeroed() && want_init_on_alloc(gfp_flags))
//		kernel_init_free_pages(page, 1 << order);

//	if (order && (gfp_flags & __GFP_COMP))
//		prep_compound_page(page, order);

//	/*
//	 * page is set pfmemalloc when ALLOC_NO_WATERMARKS was necessary to
//	 * allocate the page. The expectation is that the caller is taking
//	 * steps that will free more memory. The caller should avoid the page
//	 * being used for !PFMEMALLOC purposes.
//	 */
//	if (alloc_flags & ALLOC_NO_WATERMARKS)
//		set_page_pfmemalloc(page);
//	else
//		clear_page_pfmemalloc(page);
//}

///*
// * Go through the free lists for the given migratetype and remove
// * the smallest available page from the freelists
// */
//static __always_inline
//struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
//						int migratetype)
//{
//	unsigned int current_order;
//	struct free_area *area;
//	struct page *page;

//	/* Find a page of the appropriate size in the preferred list */
//	for (current_order = order; current_order < MAX_ORDER; ++current_order) {
//		area = &(zone->free_area[current_order]);
//		page = get_page_from_free_area(area, migratetype);
//		if (!page)
//			continue;
//		del_page_from_free_list(page, zone, current_order);
//		expand(zone, page, order, current_order, migratetype);
//		set_pcppage_migratetype(page, migratetype);
//		return page;
//	}

//	return NULL;
//}


///*
// * This array describes the order lists are fallen back to when
// * the free lists for the desirable migrate type are depleted
// */
//static int fallbacks[MIGRATE_TYPES][3] = {
//	[MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,   MIGRATE_TYPES },
//	[MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_TYPES },
//	[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE,   MIGRATE_TYPES },
//#ifdef CONFIG_CMA
//	[MIGRATE_CMA]         = { MIGRATE_TYPES }, /* Never used */
//#endif
//#ifdef CONFIG_MEMORY_ISOLATION
//	[MIGRATE_ISOLATE]     = { MIGRATE_TYPES }, /* Never used */
//#endif
//};

//#ifdef CONFIG_CMA
//static __always_inline struct page *__rmqueue_cma_fallback(struct zone *zone,
//					unsigned int order)
//{
//	return __rmqueue_smallest(zone, order, MIGRATE_CMA);
//}
//#else
//static inline struct page *__rmqueue_cma_fallback(struct zone *zone,
//					unsigned int order) { return NULL; }
//#endif

///*
// * Move the free pages in a range to the freelist tail of the requested type.
// * Note that start_page and end_pages are not aligned on a pageblock
// * boundary. If alignment is required, use move_freepages_block()
// */
//static int move_freepages(struct zone *zone,
//			  struct page *start_page, struct page *end_page,
//			  int migratetype, int *num_movable)
//{
//	struct page *page;
//	unsigned int order;
//	int pages_moved = 0;

//	for (page = start_page; page <= end_page;) {
//		if (!pfn_valid_within(page_to_pfn(page))) {
//			page++;
//			continue;
//		}

//		if (!PageBuddy(page)) {
//			/*
//			 * We assume that pages that could be isolated for
//			 * migration are movable. But we don't actually try
//			 * isolating, as that would be expensive.
//			 */
//			if (num_movable &&
//					(PageLRU(page) || __PageMovable(page)))
//				(*num_movable)++;

//			page++;
//			continue;
//		}

//		/* Make sure we are not inadvertently changing nodes */
//		VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
//		VM_BUG_ON_PAGE(page_zone(page) != zone, page);

//		order = buddy_order(page);
//		move_to_free_list(page, zone, order, migratetype);
//		page += 1 << order;
//		pages_moved += 1 << order;
//	}

//	return pages_moved;
//}

//int move_freepages_block(struct zone *zone, struct page *page,
//				int migratetype, int *num_movable)
//{
//	unsigned long start_pfn, end_pfn;
//	struct page *start_page, *end_page;

//	if (num_movable)
//		*num_movable = 0;

//	start_pfn = page_to_pfn(page);
//	start_pfn = start_pfn & ~(pageblock_nr_pages-1);
//	start_page = pfn_to_page(start_pfn);
//	end_page = start_page + pageblock_nr_pages - 1;
//	end_pfn = start_pfn + pageblock_nr_pages - 1;

//	/* Do not cross zone boundaries */
//	if (!zone_spans_pfn(zone, start_pfn))
//		start_page = page;
//	if (!zone_spans_pfn(zone, end_pfn))
//		return 0;

//	return move_freepages(zone, start_page, end_page, migratetype,
//								num_movable);
//}

//static void change_pageblock_range(struct page *pageblock_page,
//					int start_order, int migratetype)
//{
//	int nr_pageblocks = 1 << (start_order - pageblock_order);

//	while (nr_pageblocks--) {
//		set_pageblock_migratetype(pageblock_page, migratetype);
//		pageblock_page += pageblock_nr_pages;
//	}
//}

///*
// * When we are falling back to another migratetype during allocation, try to
// * steal extra free pages from the same pageblocks to satisfy further
// * allocations, instead of polluting multiple pageblocks.
// *
// * If we are stealing a relatively large buddy page, it is likely there will
// * be more free pages in the pageblock, so try to steal them all. For
// * reclaimable and unmovable allocations, we steal regardless of page size,
// * as fragmentation caused by those allocations polluting movable pageblocks
// * is worse than movable allocations stealing from unmovable and reclaimable
// * pageblocks.
// */
//static bool can_steal_fallback(unsigned int order, int start_mt)
//{
//	/*
//	 * Leaving this order check is intended, although there is
//	 * relaxed order check in next check. The reason is that
//	 * we can actually steal whole pageblock if this condition met,
//	 * but, below check doesn't guarantee it and that is just heuristic
//	 * so could be changed anytime.
//	 */
//	if (order >= pageblock_order)
//		return true;

//	if (order >= pageblock_order / 2 ||
//		start_mt == MIGRATE_RECLAIMABLE ||
//		start_mt == MIGRATE_UNMOVABLE ||
//		page_group_by_mobility_disabled)
//		return true;

//	return false;
//}

//static inline bool boost_watermark(struct zone *zone)
//{
//	unsigned long max_boost;

//	if (!watermark_boost_factor)
//		return false;
//	/*
//	 * Don't bother in zones that are unlikely to produce results.
//	 * On small machines, including kdump capture kernels running
//	 * in a small area, boosting the watermark can cause an out of
//	 * memory situation immediately.
//	 */
//	if ((pageblock_nr_pages * 4) > zone_managed_pages(zone))
//		return false;

//	max_boost = mult_frac(zone->_watermark[WMARK_HIGH],
//			watermark_boost_factor, 10000);

//	/*
//	 * high watermark may be uninitialised if fragmentation occurs
//	 * very early in boot so do not boost. We do not fall
//	 * through and boost by pageblock_nr_pages as failing
//	 * allocations that early means that reclaim is not going
//	 * to help and it may even be impossible to reclaim the
//	 * boosted watermark resulting in a hang.
//	 */
//	if (!max_boost)
//		return false;

//	max_boost = max(pageblock_nr_pages, max_boost);

//	zone->watermark_boost = min(zone->watermark_boost + pageblock_nr_pages,
//		max_boost);

//	return true;
//}

///*
// * This function implements actual steal behaviour. If order is large enough,
// * we can steal whole pageblock. If not, we first move freepages in this
// * pageblock to our migratetype and determine how many already-allocated pages
// * are there in the pageblock with a compatible migratetype. If at least half
// * of pages are free or compatible, we can change migratetype of the pageblock
// * itself, so pages freed in the future will be put on the correct free list.
// */
//static void steal_suitable_fallback(struct zone *zone, struct page *page,
//		unsigned int alloc_flags, int start_type, bool whole_block)
//{
//	unsigned int current_order = buddy_order(page);
//	int free_pages, movable_pages, alike_pages;
//	int old_block_type;

//	old_block_type = get_pageblock_migratetype(page);

//	/*
//	 * This can happen due to races and we want to prevent broken
//	 * highatomic accounting.
//	 */
//	if (is_migrate_highatomic(old_block_type))
//		goto single_page;

//	/* Take ownership for orders >= pageblock_order */
//	if (current_order >= pageblock_order) {
//		change_pageblock_range(page, current_order, start_type);
//		goto single_page;
//	}

//	/*
//	 * Boost watermarks to increase reclaim pressure to reduce the
//	 * likelihood of future fallbacks. Wake kswapd now as the node
//	 * may be balanced overall and kswapd will not wake naturally.
//	 */
//	if (boost_watermark(zone) && (alloc_flags & ALLOC_KSWAPD))
//		set_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);

//	/* We are not allowed to try stealing from the whole block */
//	if (!whole_block)
//		goto single_page;

//	free_pages = move_freepages_block(zone, page, start_type,
//						&movable_pages);
//	/*
//	 * Determine how many pages are compatible with our allocation.
//	 * For movable allocation, it's the number of movable pages which
//	 * we just obtained. For other types it's a bit more tricky.
//	 */
//	if (start_type == MIGRATE_MOVABLE) {
//		alike_pages = movable_pages;
//	} else {
//		/*
//		 * If we are falling back a RECLAIMABLE or UNMOVABLE allocation
//		 * to MOVABLE pageblock, consider all non-movable pages as
//		 * compatible. If it's UNMOVABLE falling back to RECLAIMABLE or
//		 * vice versa, be conservative since we can't distinguish the
//		 * exact migratetype of non-movable pages.
//		 */
//		if (old_block_type == MIGRATE_MOVABLE)
//			alike_pages = pageblock_nr_pages
//						- (free_pages + movable_pages);
//		else
//			alike_pages = 0;
//	}

//	/* moving whole block can fail due to zone boundary conditions */
//	if (!free_pages)
//		goto single_page;

//	/*
//	 * If a sufficient number of pages in the block are either free or of
//	 * comparable migratability as our allocation, claim the whole block.
//	 */
//	if (free_pages + alike_pages >= (1 << (pageblock_order-1)) ||
//			page_group_by_mobility_disabled)
//		set_pageblock_migratetype(page, start_type);

//	return;

//single_page:
//	move_to_free_list(page, zone, current_order, start_type);
//}

///*
// * Check whether there is a suitable fallback freepage with requested order.
// * If only_stealable is true, this function returns fallback_mt only if
// * we can steal other freepages all together. This would help to reduce
// * fragmentation due to mixed migratetype pages in one pageblock.
// */
//int find_suitable_fallback(struct free_area *area, unsigned int order,
//			int migratetype, bool only_stealable, bool *can_steal)
//{
//	int i;
//	int fallback_mt;

//	if (area->nr_free == 0)
//		return -1;

//	*can_steal = false;
//	for (i = 0;; i++) {
//		fallback_mt = fallbacks[migratetype][i];
//		if (fallback_mt == MIGRATE_TYPES)
//			break;

//		if (free_area_empty(area, fallback_mt))
//			continue;

//		if (can_steal_fallback(order, migratetype))
//			*can_steal = true;

//		if (!only_stealable)
//			return fallback_mt;

//		if (*can_steal)
//			return fallback_mt;
//	}

//	return -1;
//}

///*
// * Reserve a pageblock for exclusive use of high-order atomic allocations if
// * there are no empty page blocks that contain a page with a suitable order
// */
//static void reserve_highatomic_pageblock(struct page *page, struct zone *zone,
//				unsigned int alloc_order)
//{
//	int mt;
//	unsigned long max_managed, flags;

//	/*
//	 * Limit the number reserved to 1 pageblock or roughly 1% of a zone.
//	 * Check is race-prone but harmless.
//	 */
//	max_managed = (zone_managed_pages(zone) / 100) + pageblock_nr_pages;
//	if (zone->nr_reserved_highatomic >= max_managed)
//		return;

//	spin_lock_irqsave(&zone->lock, flags);

//	/* Recheck the nr_reserved_highatomic limit under the lock */
//	if (zone->nr_reserved_highatomic >= max_managed)
//		goto out_unlock;

//	/* Yoink! */
//	mt = get_pageblock_migratetype(page);
//	if (!is_migrate_highatomic(mt) && !is_migrate_isolate(mt)
//	    && !is_migrate_cma(mt)) {
//		zone->nr_reserved_highatomic += pageblock_nr_pages;
//		set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC);
//		move_freepages_block(zone, page, MIGRATE_HIGHATOMIC, NULL);
//	}

//out_unlock:
//	spin_unlock_irqrestore(&zone->lock, flags);
//}

///*
// * Used when an allocation is about to fail under memory pressure. This
// * potentially hurts the reliability of high-order allocations when under
// * intense memory pressure but failed atomic allocations should be easier
// * to recover from than an OOM.
// *
// * If @force is true, try to unreserve a pageblock even though highatomic
// * pageblock is exhausted.
// */
//static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
//						bool force)
//{
//	struct zonelist *zonelist = ac->zonelist;
//	unsigned long flags;
//	struct zoneref *z;
//	struct zone *zone;
//	struct page *page;
//	int order;
//	bool ret;

//	for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->highest_zoneidx,
//								ac->nodemask) {
//		/*
//		 * Preserve at least one pageblock unless memory pressure
//		 * is really high.
//		 */
//		if (!force && zone->nr_reserved_highatomic <=
//					pageblock_nr_pages)
//			continue;

//		spin_lock_irqsave(&zone->lock, flags);
//		for (order = 0; order < MAX_ORDER; order++) {
//			struct free_area *area = &(zone->free_area[order]);

//			page = get_page_from_free_area(area, MIGRATE_HIGHATOMIC);
//			if (!page)
//				continue;

//			/*
//			 * In page freeing path, migratetype change is racy so
//			 * we can counter several free pages in a pageblock
//			 * in this loop althoug we changed the pageblock type
//			 * from highatomic to ac->migratetype. So we should
//			 * adjust the count once.
//			 */
//			if (is_migrate_highatomic_page(page)) {
//				/*
//				 * It should never happen but changes to
//				 * locking could inadvertently allow a per-cpu
//				 * drain to add pages to MIGRATE_HIGHATOMIC
//				 * while unreserving so be safe and watch for
//				 * underflows.
//				 */
//				zone->nr_reserved_highatomic -= min(
//						pageblock_nr_pages,
//						zone->nr_reserved_highatomic);
//			}

//			/*
//			 * Convert to ac->migratetype and avoid the normal
//			 * pageblock stealing heuristics. Minimally, the caller
//			 * is doing the work and needs the pages. More
//			 * importantly, if the block was always converted to
//			 * MIGRATE_UNMOVABLE or another type then the number
//			 * of pageblocks that cannot be completely freed
//			 * may increase.
//			 */
//			set_pageblock_migratetype(page, ac->migratetype);
//			ret = move_freepages_block(zone, page, ac->migratetype,
//									NULL);
//			if (ret) {
//				spin_unlock_irqrestore(&zone->lock, flags);
//				return ret;
//			}
//		}
//		spin_unlock_irqrestore(&zone->lock, flags);
//	}

//	return false;
//}

///*
// * Try finding a free buddy page on the fallback list and put it on the free
// * list of requested migratetype, possibly along with other pages from the same
// * block, depending on fragmentation avoidance heuristics. Returns true if
// * fallback was found so that __rmqueue_smallest() can grab it.
// *
// * The use of signed ints for order and current_order is a deliberate
// * deviation from the rest of this file, to make the for loop
// * condition simpler.
// */
//static __always_inline bool
//__rmqueue_fallback(struct zone *zone, int order, int start_migratetype,
//						unsigned int alloc_flags)
//{
//	struct free_area *area;
//	int current_order;
//	int min_order = order;
//	struct page *page;
//	int fallback_mt;
//	bool can_steal;

//	/*
//	 * Do not steal pages from freelists belonging to other pageblocks
//	 * i.e. orders < pageblock_order. If there are no local zones free,
//	 * the zonelists will be reiterated without ALLOC_NOFRAGMENT.
//	 */
//	if (alloc_flags & ALLOC_NOFRAGMENT)
//		min_order = pageblock_order;

//	/*
//	 * Find the largest available free page in the other list. This roughly
//	 * approximates finding the pageblock with the most free pages, which
//	 * would be too costly to do exactly.
//	 */
//	for (current_order = MAX_ORDER - 1; current_order >= min_order;
//				--current_order) {
//		area = &(zone->free_area[current_order]);
//		fallback_mt = find_suitable_fallback(area, current_order,
//				start_migratetype, false, &can_steal);
//		if (fallback_mt == -1)
//			continue;

//		/*
//		 * We cannot steal all free pages from the pageblock and the
//		 * requested migratetype is movable. In that case it's better to
//		 * steal and split the smallest available page instead of the
//		 * largest available page, because even if the next movable
//		 * allocation falls back into a different pageblock than this
//		 * one, it won't cause permanent fragmentation.
//		 */
//		if (!can_steal && start_migratetype == MIGRATE_MOVABLE
//					&& current_order > order)
//			goto find_smallest;

//		goto do_steal;
//	}

//	return false;

//find_smallest:
//	for (current_order = order; current_order < MAX_ORDER;
//							current_order++) {
//		area = &(zone->free_area[current_order]);
//		fallback_mt = find_suitable_fallback(area, current_order,
//				start_migratetype, false, &can_steal);
//		if (fallback_mt != -1)
//			break;
//	}

//	/*
//	 * This should not happen - we already found a suitable fallback
//	 * when looking for the largest page.
//	 */
//	VM_BUG_ON(current_order == MAX_ORDER);

//do_steal:
//	page = get_page_from_free_area(area, fallback_mt);

//	steal_suitable_fallback(zone, page, alloc_flags, start_migratetype,
//								can_steal);

//	trace_mm_page_alloc_extfrag(page, order, current_order,
//		start_migratetype, fallback_mt);

//	return true;

//}

///*
// * Do the hard work of removing an element from the buddy allocator.
// * Call me with the zone->lock already held.
// */
//static __always_inline struct page *
//__rmqueue(struct zone *zone, unsigned int order, int migratetype,
//						unsigned int alloc_flags)
//{
//	struct page *page;

//	if (IS_ENABLED(CONFIG_CMA)) {
//		/*
//		 * Balance movable allocations between regular and CMA areas by
//		 * allocating from CMA when over half of the zone's free memory
//		 * is in the CMA area.
//		 */
//		if (alloc_flags & ALLOC_CMA &&
//		    zone_page_state(zone, NR_FREE_CMA_PAGES) >
//		    zone_page_state(zone, NR_FREE_PAGES) / 2) {
//			page = __rmqueue_cma_fallback(zone, order);
//			if (page)
//				goto out;
//		}
//	}
//retry:
//	page = __rmqueue_smallest(zone, order, migratetype);
//	if (unlikely(!page)) {
//		if (alloc_flags & ALLOC_CMA)
//			page = __rmqueue_cma_fallback(zone, order);

//		if (!page && __rmqueue_fallback(zone, order, migratetype,
//								alloc_flags))
//			goto retry;
//	}
//out:
//	if (page)
//		trace_mm_page_alloc_zone_locked(page, order, migratetype);
//	return page;
//}

///*
// * Obtain a specified number of elements from the buddy allocator, all under
// * a single hold of the lock, for efficiency.  Add them to the supplied list.
// * Returns the number of new pages which were placed at *list.
// */
//static int rmqueue_bulk(struct zone *zone, unsigned int order,
//			unsigned long count, struct list_head *list,
//			int migratetype, unsigned int alloc_flags)
//{
//	int i, alloced = 0;

//	spin_lock(&zone->lock);
//	for (i = 0; i < count; ++i) {
//		struct page *page = __rmqueue(zone, order, migratetype,
//								alloc_flags);
//		if (unlikely(page == NULL))
//			break;

//		if (unlikely(check_pcp_refill(page)))
//			continue;

//		/*
//		 * Split buddy pages returned by expand() are received here in
//		 * physical page order. The page is added to the tail of
//		 * caller's list. From the callers perspective, the linked list
//		 * is ordered by page number under some conditions. This is
//		 * useful for IO devices that can forward direction from the
//		 * head, thus also in the physical page order. This is useful
//		 * for IO devices that can merge IO requests if the physical
//		 * pages are ordered properly.
//		 */
//		list_add_tail(&page->lru, list);
//		alloced++;
//		if (is_migrate_cma(get_pcppage_migratetype(page)))
//			__mod_zone_page_state(zone, NR_FREE_CMA_PAGES,
//					      -(1 << order));
//	}

//	/*
//	 * i pages were removed from the buddy list even if some leak due
//	 * to check_pcp_refill failing so adjust NR_FREE_PAGES based
//	 * on i. Do not confuse with 'alloced' which is the number of
//	 * pages added to the pcp list.
//	 */
//	__mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
//	spin_unlock(&zone->lock);
//	return alloced;
//}

//#ifdef CONFIG_NUMA
///*
// * Called from the vmstat counter updater to drain pagesets of this
// * currently executing processor on remote nodes after they have
// * expired.
// *
// * Note that this function must be called with the thread pinned to
// * a single processor.
// */
//void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
//{
//	unsigned long flags;
//	int to_drain, batch;

//	local_irq_save(flags);
//	batch = READ_ONCE(pcp->batch);
//	to_drain = min(pcp->count, batch);
//	if (to_drain > 0)
//		free_pcppages_bulk(zone, to_drain, pcp);
//	local_irq_restore(flags);
//}
//#endif

///*
// * Drain pcplists of the indicated processor and zone.
// *
// * The processor must either be the current processor and the
// * thread pinned to the current processor or a processor that
// * is not online.
// */
//static void drain_pages_zone(unsigned int cpu, struct zone *zone)
//{
//	unsigned long flags;
//	struct per_cpu_pageset *pset;
//	struct per_cpu_pages *pcp;

//	local_irq_save(flags);
//	pset = per_cpu_ptr(zone->pageset, cpu);

//	pcp = &pset->pcp;
//	if (pcp->count)
//		free_pcppages_bulk(zone, pcp->count, pcp);
//	local_irq_restore(flags);
//}

///*
// * Drain pcplists of all zones on the indicated processor.
// *
// * The processor must either be the current processor and the
// * thread pinned to the current processor or a processor that
// * is not online.
// */
//static void drain_pages(unsigned int cpu)
//{
//	struct zone *zone;

//	for_each_populated_zone(zone) {
//		drain_pages_zone(cpu, zone);
//	}
//}

///*
// * Spill all of this CPU's per-cpu pages back into the buddy allocator.
// *
// * The CPU has to be pinned. When zone parameter is non-NULL, spill just
// * the single zone's pages.
// */
//void drain_local_pages(struct zone *zone)
//{
//	int cpu = smp_processor_id();

//	if (zone)
//		drain_pages_zone(cpu, zone);
//	else
//		drain_pages(cpu);
//}

//static void drain_local_pages_wq(struct work_struct *work)
//{
//	struct pcpu_drain *drain;

//	drain = container_of(work, struct pcpu_drain, work);

//	/*
//	 * drain_all_pages doesn't use proper cpu hotplug protection so
//	 * we can race with cpu offline when the WQ can move this from
//	 * a cpu pinned worker to an unbound one. We can operate on a different
//	 * cpu which is allright but we also have to make sure to not move to
//	 * a different one.
//	 */
//	preempt_disable();
//	drain_local_pages(drain->zone);
//	preempt_enable();
//}

///*
// * Spill all the per-cpu pages from all CPUs back into the buddy allocator.
// *
// * When zone parameter is non-NULL, spill just the single zone's pages.
// *
// * Note that this can be extremely slow as the draining happens in a workqueue.
// */
//void drain_all_pages(struct zone *zone)
//{
//	int cpu;

//	/*
//	 * Allocate in the BSS so we wont require allocation in
//	 * direct reclaim path for CONFIG_CPUMASK_OFFSTACK=y
//	 */
//	static cpumask_t cpus_with_pcps;

//	/*
//	 * Make sure nobody triggers this path before mm_percpu_wq is fully
//	 * initialized.
//	 */
//	if (WARN_ON_ONCE(!mm_percpu_wq))
//		return;

//	/*
//	 * Do not drain if one is already in progress unless it's specific to
//	 * a zone. Such callers are primarily CMA and memory hotplug and need
//	 * the drain to be complete when the call returns.
//	 */
//	if (unlikely(!mutex_trylock(&pcpu_drain_mutex))) {
//		if (!zone)
//			return;
//		mutex_lock(&pcpu_drain_mutex);
//	}

//	/*
//	 * We don't care about racing with CPU hotplug event
//	 * as offline notification will cause the notified
//	 * cpu to drain that CPU pcps and on_each_cpu_mask
//	 * disables preemption as part of its processing
//	 */
//	for_each_online_cpu(cpu) {
//		struct per_cpu_pageset *pcp;
//		struct zone *z;
//		bool has_pcps = false;

//		if (zone) {
//			pcp = per_cpu_ptr(zone->pageset, cpu);
//			if (pcp->pcp.count)
//				has_pcps = true;
//		} else {
//			for_each_populated_zone(z) {
//				pcp = per_cpu_ptr(z->pageset, cpu);
//				if (pcp->pcp.count) {
//					has_pcps = true;
//					break;
//				}
//			}
//		}

//		if (has_pcps)
//			cpumask_set_cpu(cpu, &cpus_with_pcps);
//		else
//			cpumask_clear_cpu(cpu, &cpus_with_pcps);
//	}

//	for_each_cpu(cpu, &cpus_with_pcps) {
//		struct pcpu_drain *drain = per_cpu_ptr(&pcpu_drain, cpu);

//		drain->zone = zone;
//		INIT_WORK(&drain->work, drain_local_pages_wq);
//		queue_work_on(cpu, mm_percpu_wq, &drain->work);
//	}
//	for_each_cpu(cpu, &cpus_with_pcps)
//		flush_work(&per_cpu_ptr(&pcpu_drain, cpu)->work);

//	mutex_unlock(&pcpu_drain_mutex);
//}

//#ifdef CONFIG_HIBERNATION

///*
// * Touch the watchdog for every WD_PAGE_COUNT pages.
// */
//#define WD_PAGE_COUNT	(128*1024)

//void mark_free_pages(struct zone *zone)
//{
//	unsigned long pfn, max_zone_pfn, page_count = WD_PAGE_COUNT;
//	unsigned long flags;
//	unsigned int order, t;
//	struct page *page;

//	if (zone_is_empty(zone))
//		return;

//	spin_lock_irqsave(&zone->lock, flags);

//	max_zone_pfn = zone_end_pfn(zone);
//	for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
//		if (pfn_valid(pfn)) {
//			page = pfn_to_page(pfn);

//			if (!--page_count) {
//				touch_nmi_watchdog();
//				page_count = WD_PAGE_COUNT;
//			}

//			if (page_zone(page) != zone)
//				continue;

//			if (!swsusp_page_is_forbidden(page))
//				swsusp_unset_page_free(page);
//		}

//	for_each_migratetype_order(order, t) {
//		list_for_each_entry(page,
//				&zone->free_area[order].free_list[t], lru) {
//			unsigned long i;

//			pfn = page_to_pfn(page);
//			for (i = 0; i < (1UL << order); i++) {
//				if (!--page_count) {
//					touch_nmi_watchdog();
//					page_count = WD_PAGE_COUNT;
//				}
//				swsusp_set_page_free(pfn_to_page(pfn + i));
//			}
//		}
//	}
//	spin_unlock_irqrestore(&zone->lock, flags);
//}
//#endif /* CONFIG_PM */

//static bool free_unref_page_prepare(struct page *page, unsigned long pfn)
//{
//	int migratetype;

//	if (!free_pcp_prepare(page))
//		return false;

//	migratetype = get_pfnblock_migratetype(page, pfn);
//	set_pcppage_migratetype(page, migratetype);
//	return true;
//}

//static void free_unref_page_commit(struct page *page, unsigned long pfn)
//{
//	struct zone *zone = page_zone(page);
//	struct per_cpu_pages *pcp;
//	int migratetype;

//	migratetype = get_pcppage_migratetype(page);
//	__count_vm_event(PGFREE);

//	/*
//	 * We only track unmovable, reclaimable and movable on pcp lists.
//	 * Free ISOLATE pages back to the allocator because they are being
//	 * offlined but treat HIGHATOMIC as movable pages so we can get those
//	 * areas back if necessary. Otherwise, we may have to free
//	 * excessively into the page allocator
//	 */
//	if (migratetype >= MIGRATE_PCPTYPES) {
//		if (unlikely(is_migrate_isolate(migratetype))) {
//			free_one_page(zone, page, pfn, 0, migratetype,
//				      FPI_NONE);
//			return;
//		}
//		migratetype = MIGRATE_MOVABLE;
//	}

//	pcp = &this_cpu_ptr(zone->pageset)->pcp;
//	list_add(&page->lru, &pcp->lists[migratetype]);
//	pcp->count++;
//	if (pcp->count >= pcp->high) {
//		unsigned long batch = READ_ONCE(pcp->batch);
//		free_pcppages_bulk(zone, batch, pcp);
//	}
//}

///*
// * Free a 0-order page
// */
//void free_unref_page(struct page *page)
//{
//	unsigned long flags;
//	unsigned long pfn = page_to_pfn(page);

//	if (!free_unref_page_prepare(page, pfn))
//		return;

//	local_irq_save(flags);
//	free_unref_page_commit(page, pfn);
//	local_irq_restore(flags);
//}

///*
// * Free a list of 0-order pages
// */
//void free_unref_page_list(struct list_head *list)
//{
//	struct page *page, *next;
//	unsigned long flags, pfn;
//	int batch_count = 0;

//	/* Prepare pages for freeing */
//	list_for_each_entry_safe(page, next, list, lru) {
//		pfn = page_to_pfn(page);
//		if (!free_unref_page_prepare(page, pfn))
//			list_del(&page->lru);
//		set_page_private(page, pfn);
//	}

//	local_irq_save(flags);
//	list_for_each_entry_safe(page, next, list, lru) {
//		unsigned long pfn = page_private(page);

//		set_page_private(page, 0);
//		trace_mm_page_free_batched(page);
//		free_unref_page_commit(page, pfn);

//		/*
//		 * Guard against excessive IRQ disabled times when we get
//		 * a large list of pages to free.
//		 */
//		if (++batch_count == SWAP_CLUSTER_MAX) {
//			local_irq_restore(flags);
//			batch_count = 0;
//			local_irq_save(flags);
//		}
//	}
//	local_irq_restore(flags);
//}

///*
// * split_page takes a non-compound higher-order page, and splits it into
// * n (1<<order) sub-pages: page[0..n]
// * Each sub-page must be freed individually.
// *
// * Note: this is probably too low level an operation for use in drivers.
// * Please consult with lkml before using this in your driver.
// */
//void split_page(struct page *page, unsigned int order)
//{
//	int i;

//	VM_BUG_ON_PAGE(PageCompound(page), page);
//	VM_BUG_ON_PAGE(!page_count(page), page);

//	for (i = 1; i < (1 << order); i++)
//		set_page_refcounted(page + i);
//	split_page_owner(page, 1 << order);
//	split_page_memcg(page, 1 << order);
//}
//EXPORT_SYMBOL_GPL(split_page);

//int __isolate_free_page(struct page *page, unsigned int order)
//{
//	unsigned long watermark;
//	struct zone *zone;
//	int mt;

//	BUG_ON(!PageBuddy(page));

//	zone = page_zone(page);
//	mt = get_pageblock_migratetype(page);

//	if (!is_migrate_isolate(mt)) {
//		/*
//		 * Obey watermarks as if the page was being allocated. We can
//		 * emulate a high-order watermark check with a raised order-0
//		 * watermark, because we already know our high-order page
//		 * exists.
//		 */
//		watermark = zone->_watermark[WMARK_MIN] + (1UL << order);
//		if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA))
//			return 0;

//		__mod_zone_freepage_state(zone, -(1UL << order), mt);
//	}

//	/* Remove page from free list */

//	del_page_from_free_list(page, zone, order);

//	/*
//	 * Set the pageblock if the isolated page is at least half of a
//	 * pageblock
//	 */
//	if (order >= pageblock_order - 1) {
//		struct page *endpage = page + (1 << order) - 1;
//		for (; page < endpage; page += pageblock_nr_pages) {
//			int mt = get_pageblock_migratetype(page);
//			if (!is_migrate_isolate(mt) && !is_migrate_cma(mt)
//			    && !is_migrate_highatomic(mt))
//				set_pageblock_migratetype(page,
//							  MIGRATE_MOVABLE);
//		}
//	}


//	return 1UL << order;
//}

///**
// * __putback_isolated_page - Return a now-isolated page back where we got it
// * @page: Page that was isolated
// * @order: Order of the isolated page
// * @mt: The page's pageblock's migratetype
// *
// * This function is meant to return a page pulled from the free lists via
// * __isolate_free_page back to the free lists they were pulled from.
// */
//void __putback_isolated_page(struct page *page, unsigned int order, int mt)
//{
//	struct zone *zone = page_zone(page);

//	/* zone lock should be held when this function is called */
//	lockdep_assert_held(&zone->lock);

//	/* Return isolated page to tail of freelist. */
//	__free_one_page(page, page_to_pfn(page), zone, order, mt,
//			FPI_SKIP_REPORT_NOTIFY | FPI_TO_TAIL);
//}

///*
// * Update NUMA hit/miss statistics
// *
// * Must be called with interrupts disabled.
// */
//static inline void zone_statistics(struct zone *preferred_zone, struct zone *z)
//{
//#ifdef CONFIG_NUMA
//	enum numa_stat_item local_stat = NUMA_LOCAL;

//	/* skip numa counters update if numa stats is disabled */
//	if (!static_branch_likely(&vm_numa_stat_key))
//		return;

//	if (zone_to_nid(z) != numa_node_id())
//		local_stat = NUMA_OTHER;

//	if (zone_to_nid(z) == zone_to_nid(preferred_zone))
//		__inc_numa_state(z, NUMA_HIT);
//	else {
//		__inc_numa_state(z, NUMA_MISS);
//		__inc_numa_state(preferred_zone, NUMA_FOREIGN);
//	}
//	__inc_numa_state(z, local_stat);
//#endif
//}

///* Remove page from the per-cpu list, caller must protect the list */
//static struct page *__rmqueue_pcplist(struct zone *zone, int migratetype,
//			unsigned int alloc_flags,
//			struct per_cpu_pages *pcp,
//			struct list_head *list)
//{
//	struct page *page;

//	do {
//		if (list_empty(list)) {
//			pcp->count += rmqueue_bulk(zone, 0,
//					pcp->batch, list,
//					migratetype, alloc_flags);
//			if (unlikely(list_empty(list)))
//				return NULL;
//		}

//		page = list_first_entry(list, struct page, lru);
//		list_del(&page->lru);
//		pcp->count--;
//	} while (check_new_pcp(page));

//	return page;
//}

///* Lock and remove page from the per-cpu list */
//static struct page *rmqueue_pcplist(struct zone *preferred_zone,
//			struct zone *zone, gfp_t gfp_flags,
//			int migratetype, unsigned int alloc_flags)
//{
//	struct per_cpu_pages *pcp;
//	struct list_head *list;
//	struct page *page;
//	unsigned long flags;

//	local_irq_save(flags);
//	pcp = &this_cpu_ptr(zone->pageset)->pcp;
//	list = &pcp->lists[migratetype];
//	page = __rmqueue_pcplist(zone,  migratetype, alloc_flags, pcp, list);
//	if (page) {
//		__count_zid_vm_events(PGALLOC, page_zonenum(page), 1);
//		zone_statistics(preferred_zone, zone);
//	}
//	local_irq_restore(flags);
//	return page;
//}

///*
// * Allocate a page from the given zone. Use pcplists for order-0 allocations.
// */
//static inline
//struct page *rmqueue(struct zone *preferred_zone,
//			struct zone *zone, unsigned int order,
//			gfp_t gfp_flags, unsigned int alloc_flags,
//			int migratetype)
//{
//	unsigned long flags;
//	struct page *page;

//	if (likely(order == 0)) {
//		/*
//		 * MIGRATE_MOVABLE pcplist could have the pages on CMA area and
//		 * we need to skip it when CMA area isn't allowed.
//		 */
//		if (!IS_ENABLED(CONFIG_CMA) || alloc_flags & ALLOC_CMA ||
//				migratetype != MIGRATE_MOVABLE) {
//			page = rmqueue_pcplist(preferred_zone, zone, gfp_flags,
//					migratetype, alloc_flags);
//			goto out;
//		}
//	}

//	/*
//	 * We most definitely don't want callers attempting to
//	 * allocate greater than order-1 page units with __GFP_NOFAIL.
//	 */
//	WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
//	spin_lock_irqsave(&zone->lock, flags);

//	do {
//		page = NULL;
//		/*
//		 * order-0 request can reach here when the pcplist is skipped
//		 * due to non-CMA allocation context. HIGHATOMIC area is
//		 * reserved for high-order atomic allocation, so order-0
//		 * request should skip it.
//		 */
//		if (order > 0 && alloc_flags & ALLOC_HARDER) {
//			page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
//			if (page)
//				trace_mm_page_alloc_zone_locked(page, order, migratetype);
//		}
//		if (!page)
//			page = __rmqueue(zone, order, migratetype, alloc_flags);
//	} while (page && check_new_pages(page, order));
//	spin_unlock(&zone->lock);
//	if (!page)
//		goto failed;
//	__mod_zone_freepage_state(zone, -(1 << order),
//				  get_pcppage_migratetype(page));

//	__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
//	zone_statistics(preferred_zone, zone);
//	local_irq_restore(flags);

//out:
//	/* Separate test+clear to avoid unnecessary atomics */
//	if (test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags)) {
//		clear_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
//		wakeup_kswapd(zone, 0, 0, zone_idx(zone));
//	}

//	VM_BUG_ON_PAGE(page && bad_range(zone, page), page);
//	return page;

//failed:
//	local_irq_restore(flags);
//	return NULL;
//}

//#ifdef CONFIG_FAIL_PAGE_ALLOC

//static struct {
//	struct fault_attr attr;

//	bool ignore_gfp_highmem;
//	bool ignore_gfp_reclaim;
//	u32 min_order;
//} fail_page_alloc = {
//	.attr = FAULT_ATTR_INITIALIZER,
//	.ignore_gfp_reclaim = true,
//	.ignore_gfp_highmem = true,
//	.min_order = 1,
//};

//static int __init setup_fail_page_alloc(char *str)
//{
//	return setup_fault_attr(&fail_page_alloc.attr, str);
//}
//__setup("fail_page_alloc=", setup_fail_page_alloc);

//static bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
//{
//	if (order < fail_page_alloc.min_order)
//		return false;
//	if (gfp_mask & __GFP_NOFAIL)
//		return false;
//	if (fail_page_alloc.ignore_gfp_highmem && (gfp_mask & __GFP_HIGHMEM))
//		return false;
//	if (fail_page_alloc.ignore_gfp_reclaim &&
//			(gfp_mask & __GFP_DIRECT_RECLAIM))
//		return false;

//	return should_fail(&fail_page_alloc.attr, 1 << order);
//}

//#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS

//static int __init fail_page_alloc_debugfs(void)
//{
//	umode_t mode = S_IFREG | 0600;
//	struct dentry *dir;

//	dir = fault_create_debugfs_attr("fail_page_alloc", NULL,
//					&fail_page_alloc.attr);

//	debugfs_create_bool("ignore-gfp-wait", mode, dir,
//			    &fail_page_alloc.ignore_gfp_reclaim);
//	debugfs_create_bool("ignore-gfp-highmem", mode, dir,
//			    &fail_page_alloc.ignore_gfp_highmem);
//	debugfs_create_u32("min-order", mode, dir, &fail_page_alloc.min_order);

//	return 0;
//}

//late_initcall(fail_page_alloc_debugfs);

//#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */

//#else /* CONFIG_FAIL_PAGE_ALLOC */

//static inline bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
//{
//	return false;
//}

//#endif /* CONFIG_FAIL_PAGE_ALLOC */

//noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
//{
//	return __should_fail_alloc_page(gfp_mask, order);
//}
//ALLOW_ERROR_INJECTION(should_fail_alloc_page, TRUE);

//static inline long __zone_watermark_unusable_free(struct zone *z,
//				unsigned int order, unsigned int alloc_flags)
//{
//	const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM));
//	long unusable_free = (1 << order) - 1;

//	/*
//	 * If the caller does not have rights to ALLOC_HARDER then subtract
//	 * the high-atomic reserves. This will over-estimate the size of the
//	 * atomic reserve but it avoids a search.
//	 */
//	if (likely(!alloc_harder))
//		unusable_free += z->nr_reserved_highatomic;

//#ifdef CONFIG_CMA
//	/* If allocation can't use CMA areas don't use free CMA pages */
//	if (!(alloc_flags & ALLOC_CMA))
//		unusable_free += zone_page_state(z, NR_FREE_CMA_PAGES);
//#endif

//	return unusable_free;
//}

///*
// * Return true if free base pages are above 'mark'. For high-order checks it
// * will return true of the order-0 watermark is reached and there is at least
// * one free page of a suitable size. Checking now avoids taking the zone lock
// * to check in the allocation paths if no pages are free.
// */
//bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
//			 int highest_zoneidx, unsigned int alloc_flags,
//			 long free_pages)
//{
//	long min = mark;
//	int o;
//	const bool alloc_harder = (alloc_flags & (ALLOC_HARDER|ALLOC_OOM));

//	/* free_pages may go negative - that's OK */
//	free_pages -= __zone_watermark_unusable_free(z, order, alloc_flags);

//	if (alloc_flags & ALLOC_HIGH)
//		min -= min / 2;

//	if (unlikely(alloc_harder)) {
//		/*
//		 * OOM victims can try even harder than normal ALLOC_HARDER
//		 * users on the grounds that it's definitely going to be in
//		 * the exit path shortly and free memory. Any allocation it
//		 * makes during the free path will be small and short-lived.
//		 */
//		if (alloc_flags & ALLOC_OOM)
//			min -= min / 2;
//		else
//			min -= min / 4;
//	}

//	/*
//	 * Check watermarks for an order-0 allocation request. If these
//	 * are not met, then a high-order request also cannot go ahead
//	 * even if a suitable page happened to be free.
//	 */
//	if (free_pages <= min + z->lowmem_reserve[highest_zoneidx])
//		return false;

//	/* If this is an order-0 request then the watermark is fine */
//	if (!order)
//		return true;

//	/* For a high-order request, check at least one suitable page is free */
//	for (o = order; o < MAX_ORDER; o++) {
//		struct free_area *area = &z->free_area[o];
//		int mt;

//		if (!area->nr_free)
//			continue;

//		for (mt = 0; mt < MIGRATE_PCPTYPES; mt++) {
//			if (!free_area_empty(area, mt))
//				return true;
//		}

//#ifdef CONFIG_CMA
//		if ((alloc_flags & ALLOC_CMA) &&
//		    !free_area_empty(area, MIGRATE_CMA)) {
//			return true;
//		}
//#endif
//		if (alloc_harder && !free_area_empty(area, MIGRATE_HIGHATOMIC))
//			return true;
//	}
//	return false;
//}

//bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
//		      int highest_zoneidx, unsigned int alloc_flags)
//{
//	return __zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
//					zone_page_state(z, NR_FREE_PAGES));
//}

//static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
//				unsigned long mark, int highest_zoneidx,
//				unsigned int alloc_flags, gfp_t gfp_mask)
//{
//	long free_pages;

//	free_pages = zone_page_state(z, NR_FREE_PAGES);

//	/*
//	 * Fast check for order-0 only. If this fails then the reserves
//	 * need to be calculated.
//	 */
//	if (!order) {
//		long fast_free;

//		fast_free = free_pages;
//		fast_free -= __zone_watermark_unusable_free(z, 0, alloc_flags);
//		if (fast_free > mark + z->lowmem_reserve[highest_zoneidx])
//			return true;
//	}

//	if (__zone_watermark_ok(z, order, mark, highest_zoneidx, alloc_flags,
//					free_pages))
//		return true;
//	/*
//	 * Ignore watermark boosting for GFP_ATOMIC order-0 allocations
//	 * when checking the min watermark. The min watermark is the
//	 * point where boosting is ignored so that kswapd is woken up
//	 * when below the low watermark.
//	 */
//	if (unlikely(!order && (gfp_mask & __GFP_ATOMIC) && z->watermark_boost
//		&& ((alloc_flags & ALLOC_WMARK_MASK) == WMARK_MIN))) {
//		mark = z->_watermark[WMARK_MIN];
//		return __zone_watermark_ok(z, order, mark, highest_zoneidx,
//					alloc_flags, free_pages);
//	}

//	return false;
//}

//bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
//			unsigned long mark, int highest_zoneidx)
//{
//	long free_pages = zone_page_state(z, NR_FREE_PAGES);

//	if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)
//		free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);

//	return __zone_watermark_ok(z, order, mark, highest_zoneidx, 0,
//								free_pages);
//}

//#ifdef CONFIG_NUMA
//static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
//{
//	return node_distance(zone_to_nid(local_zone), zone_to_nid(zone)) <=
//				node_reclaim_distance;
//}
//#else	/* CONFIG_NUMA */
//static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
//{
//	return true;
//}
//#endif	/* CONFIG_NUMA */

///*
// * The restriction on ZONE_DMA32 as being a suitable zone to use to avoid
// * fragmentation is subtle. If the preferred zone was HIGHMEM then
// * premature use of a lower zone may cause lowmem pressure problems that
// * are worse than fragmentation. If the next zone is ZONE_DMA then it is
// * probably too small. It only makes sense to spread allocations to avoid
// * fragmentation between the Normal and DMA32 zones.
// */
//static inline unsigned int
//alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
//{
//	unsigned int alloc_flags;

//	/*
//	 * __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
//	 * to save a branch.
//	 */
//	alloc_flags = (__force int) (gfp_mask & __GFP_KSWAPD_RECLAIM);

//#ifdef CONFIG_ZONE_DMA32
//	if (!zone)
//		return alloc_flags;

//	if (zone_idx(zone) != ZONE_NORMAL)
//		return alloc_flags;

//	/*
//	 * If ZONE_DMA32 exists, assume it is the one after ZONE_NORMAL and
//	 * the pointer is within zone->zone_pgdat->node_zones[]. Also assume
//	 * on UMA that if Normal is populated then so is DMA32.
//	 */
//	BUILD_BUG_ON(ZONE_NORMAL - ZONE_DMA32 != 1);
//	if (nr_online_nodes > 1 && !populated_zone(--zone))
//		return alloc_flags;

//	alloc_flags |= ALLOC_NOFRAGMENT;
//#endif /* CONFIG_ZONE_DMA32 */
//	return alloc_flags;
//}

//static inline unsigned int current_alloc_flags(gfp_t gfp_mask,
//					unsigned int alloc_flags)
//{
//#ifdef CONFIG_CMA
//	unsigned int pflags = current->flags;

//	if (!(pflags & PF_MEMALLOC_NOCMA) &&
//			gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
//		alloc_flags |= ALLOC_CMA;

//#endif
//	return alloc_flags;
//}

///*
// * get_page_from_freelist goes through the zonelist trying to allocate
// * a page.
// */
//static struct page *
//get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
//						const struct alloc_context *ac)
//{
//	struct zoneref *z;
//	struct zone *zone;
//	struct pglist_data *last_pgdat_dirty_limit = NULL;
//	bool no_fallback;

//retry:
//	/*
//	 * Scan zonelist, looking for a zone with enough free.
//	 * See also __cpuset_node_allowed() comment in kernel/cpuset.c.
//	 */
//	no_fallback = alloc_flags & ALLOC_NOFRAGMENT;
//	z = ac->preferred_zoneref;
//	for_next_zone_zonelist_nodemask(zone, z, ac->highest_zoneidx,
//					ac->nodemask) {
//		struct page *page;
//		unsigned long mark;

//		if (cpusets_enabled() &&
//			(alloc_flags & ALLOC_CPUSET) &&
//			!__cpuset_zone_allowed(zone, gfp_mask))
//				continue;
//		/*
//		 * When allocating a page cache page for writing, we
//		 * want to get it from a node that is within its dirty
//		 * limit, such that no single node holds more than its
//		 * proportional share of globally allowed dirty pages.
//		 * The dirty limits take into account the node's
//		 * lowmem reserves and high watermark so that kswapd
//		 * should be able to balance it without having to
//		 * write pages from its LRU list.
//		 *
//		 * XXX: For now, allow allocations to potentially
//		 * exceed the per-node dirty limit in the slowpath
//		 * (spread_dirty_pages unset) before going into reclaim,
//		 * which is important when on a NUMA setup the allowed
//		 * nodes are together not big enough to reach the
//		 * global limit.  The proper fix for these situations
//		 * will require awareness of nodes in the
//		 * dirty-throttling and the flusher threads.
//		 */
//		if (ac->spread_dirty_pages) {
//			if (last_pgdat_dirty_limit == zone->zone_pgdat)
//				continue;

//			if (!node_dirty_ok(zone->zone_pgdat)) {
//				last_pgdat_dirty_limit = zone->zone_pgdat;
//				continue;
//			}
//		}

//		if (no_fallback && nr_online_nodes > 1 &&
//		    zone != ac->preferred_zoneref->zone) {
//			int local_nid;

//			/*
//			 * If moving to a remote node, retry but allow
//			 * fragmenting fallbacks. Locality is more important
//			 * than fragmentation avoidance.
//			 */
//			local_nid = zone_to_nid(ac->preferred_zoneref->zone);
//			if (zone_to_nid(zone) != local_nid) {
//				alloc_flags &= ~ALLOC_NOFRAGMENT;
//				goto retry;
//			}
//		}

//		mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
//		if (!zone_watermark_fast(zone, order, mark,
//				       ac->highest_zoneidx, alloc_flags,
//				       gfp_mask)) {
//			int ret;

//#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
//			/*
//			 * Watermark failed for this zone, but see if we can
//			 * grow this zone if it contains deferred pages.
//			 */
//			if (static_branch_unlikely(&deferred_pages)) {
//				if (_deferred_grow_zone(zone, order))
//					goto try_this_zone;
//			}
//#endif
//			/* Checked here to keep the fast path fast */
//			BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK);
//			if (alloc_flags & ALLOC_NO_WATERMARKS)
//				goto try_this_zone;

//			if (node_reclaim_mode == 0 ||
//			    !zone_allows_reclaim(ac->preferred_zoneref->zone, zone))
//				continue;

//			ret = node_reclaim(zone->zone_pgdat, gfp_mask, order);
//			switch (ret) {
//			case NODE_RECLAIM_NOSCAN:
//				/* did not scan */
//				continue;
//			case NODE_RECLAIM_FULL:
//				/* scanned but unreclaimable */
//				continue;
//			default:
//				/* did we reclaim enough */
//				if (zone_watermark_ok(zone, order, mark,
//					ac->highest_zoneidx, alloc_flags))
//					goto try_this_zone;

//				continue;
//			}
//		}

//try_this_zone:
//		page = rmqueue(ac->preferred_zoneref->zone, zone, order,
//				gfp_mask, alloc_flags, ac->migratetype);
//		if (page) {
//			prep_new_page(page, order, gfp_mask, alloc_flags);

//			/*
//			 * If this is a high-order atomic allocation then check
//			 * if the pageblock should be reserved for the future
//			 */
//			if (unlikely(order && (alloc_flags & ALLOC_HARDER)))
//				reserve_highatomic_pageblock(page, zone, order);

//			return page;
//		} else {
//#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
//			/* Try again if zone has deferred pages */
//			if (static_branch_unlikely(&deferred_pages)) {
//				if (_deferred_grow_zone(zone, order))
//					goto try_this_zone;
//			}
//#endif
//		}
//	}

//	/*
//	 * It's possible on a UMA machine to get through all zones that are
//	 * fragmented. If avoiding fragmentation, reset and try again.
//	 */
//	if (no_fallback) {
//		alloc_flags &= ~ALLOC_NOFRAGMENT;
//		goto retry;
//	}

//	return NULL;
//}

//static void warn_alloc_show_mem(gfp_t gfp_mask, nodemask_t *nodemask)
//{
//	unsigned int filter = SHOW_MEM_FILTER_NODES;

//	/*
//	 * This documents exceptions given to allocations in certain
//	 * contexts that are allowed to allocate outside current's set
//	 * of allowed nodes.
//	 */
//	if (!(gfp_mask & __GFP_NOMEMALLOC))
//		if (tsk_is_oom_victim(current) ||
//		    (current->flags & (PF_MEMALLOC | PF_EXITING)))
//			filter &= ~SHOW_MEM_FILTER_NODES;
//	if (in_interrupt() || !(gfp_mask & __GFP_DIRECT_RECLAIM))
//		filter &= ~SHOW_MEM_FILTER_NODES;

//	show_mem(filter, nodemask);
//}

//void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
//{
//	struct va_format vaf;
//	va_list args;
//	static DEFINE_RATELIMIT_STATE(nopage_rs, 10*HZ, 1);

//	if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs))
//		return;

//	va_start(args, fmt);
//	vaf.fmt = fmt;
//	vaf.va = &args;
//	pr_warn("%s: %pV, mode:%#x(%pGg), nodemask=%*pbl",
//			current->comm, &vaf, gfp_mask, &gfp_mask,
//			nodemask_pr_args(nodemask));
//	va_end(args);

//	cpuset_print_current_mems_allowed();
//	pr_cont("\n");
//	dump_stack();
//	warn_alloc_show_mem(gfp_mask, nodemask);
//}

//static inline struct page *
//__alloc_pages_cpuset_fallback(gfp_t gfp_mask, unsigned int order,
//			      unsigned int alloc_flags,
//			      const struct alloc_context *ac)
//{
//	struct page *page;

//	page = get_page_from_freelist(gfp_mask, order,
//			alloc_flags|ALLOC_CPUSET, ac);
//	/*
//	 * fallback to ignore cpuset restriction if our nodes
//	 * are depleted
//	 */
//	if (!page)
//		page = get_page_from_freelist(gfp_mask, order,
//				alloc_flags, ac);

//	return page;
//}

//static inline struct page *
//__alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
//	const struct alloc_context *ac, unsigned long *did_some_progress)
//{
//	struct oom_control oc = {
//		.zonelist = ac->zonelist,
//		.nodemask = ac->nodemask,
//		.memcg = NULL,
//		.gfp_mask = gfp_mask,
//		.order = order,
//	};
//	struct page *page;

//	*did_some_progress = 0;

//	/*
//	 * Acquire the oom lock.  If that fails, somebody else is
//	 * making progress for us.
//	 */
//	if (!mutex_trylock(&oom_lock)) {
//		*did_some_progress = 1;
//		schedule_timeout_uninterruptible(1);
//		return NULL;
//	}

//	/*
//	 * Go through the zonelist yet one more time, keep very high watermark
//	 * here, this is only to catch a parallel oom killing, we must fail if
//	 * we're still under heavy pressure. But make sure that this reclaim
//	 * attempt shall not depend on __GFP_DIRECT_RECLAIM && !__GFP_NORETRY
//	 * allocation which will never fail due to oom_lock already held.
//	 */
//	page = get_page_from_freelist((gfp_mask | __GFP_HARDWALL) &
//				      ~__GFP_DIRECT_RECLAIM, order,
//				      ALLOC_WMARK_HIGH|ALLOC_CPUSET, ac);
//	if (page)
//		goto out;

//	/* Coredumps can quickly deplete all memory reserves */
//	if (current->flags & PF_DUMPCORE)
//		goto out;
//	/* The OOM killer will not help higher order allocs */
//	if (order > PAGE_ALLOC_COSTLY_ORDER)
//		goto out;
//	/*
//	 * We have already exhausted all our reclaim opportunities without any
//	 * success so it is time to admit defeat. We will skip the OOM killer
//	 * because it is very likely that the caller has a more reasonable
//	 * fallback than shooting a random task.
//	 *
//	 * The OOM killer may not free memory on a specific node.
//	 */
//	if (gfp_mask & (__GFP_RETRY_MAYFAIL | __GFP_THISNODE))
//		goto out;
//	/* The OOM killer does not needlessly kill tasks for lowmem */
//	if (ac->highest_zoneidx < ZONE_NORMAL)
//		goto out;
//	if (pm_suspended_storage())
//		goto out;
//	/*
//	 * XXX: GFP_NOFS allocations should rather fail than rely on
//	 * other request to make a forward progress.
//	 * We are in an unfortunate situation where out_of_memory cannot
//	 * do much for this context but let's try it to at least get
//	 * access to memory reserved if the current task is killed (see
//	 * out_of_memory). Once filesystems are ready to handle allocation
//	 * failures more gracefully we should just bail out here.
//	 */

//	/* Exhausted what can be done so it's blame time */
//	if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) {
//		*did_some_progress = 1;

//		/*
//		 * Help non-failing allocations by giving them access to memory
//		 * reserves
//		 */
//		if (gfp_mask & __GFP_NOFAIL)
//			page = __alloc_pages_cpuset_fallback(gfp_mask, order,
//					ALLOC_NO_WATERMARKS, ac);
//	}
//out:
//	mutex_unlock(&oom_lock);
//	return page;
//}

///*
// * Maximum number of compaction retries wit a progress before OOM
// * killer is consider as the only way to move forward.
// */
//#define MAX_COMPACT_RETRIES 16

//#ifdef CONFIG_COMPACTION
///* Try memory compaction for high-order allocations before reclaim */
//static struct page *
//__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
//		unsigned int alloc_flags, const struct alloc_context *ac,
//		enum compact_priority prio, enum compact_result *compact_result)
//{
//	struct page *page = NULL;
//	unsigned long pflags;
//	unsigned int noreclaim_flag;

//	if (!order)
//		return NULL;

//	psi_memstall_enter(&pflags);
//	noreclaim_flag = memalloc_noreclaim_save();

//	*compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
//								prio, &page);

//	memalloc_noreclaim_restore(noreclaim_flag);
//	psi_memstall_leave(&pflags);

//	/*
//	 * At least in one zone compaction wasn't deferred or skipped, so let's
//	 * count a compaction stall
//	 */
//	count_vm_event(COMPACTSTALL);

//	/* Prep a captured page if available */
//	if (page)
//		prep_new_page(page, order, gfp_mask, alloc_flags);

//	/* Try get a page from the freelist if available */
//	if (!page)
//		page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);

//	if (page) {
//		struct zone *zone = page_zone(page);

//		zone->compact_blockskip_flush = false;
//		compaction_defer_reset(zone, order, true);
//		count_vm_event(COMPACTSUCCESS);
//		return page;
//	}

//	/*
//	 * It's bad if compaction run occurs and fails. The most likely reason
//	 * is that pages exist, but not enough to satisfy watermarks.
//	 */
//	count_vm_event(COMPACTFAIL);

//	cond_resched();

//	return NULL;
//}

//static inline bool
//should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
//		     enum compact_result compact_result,
//		     enum compact_priority *compact_priority,
//		     int *compaction_retries)
//{
//	int max_retries = MAX_COMPACT_RETRIES;
//	int min_priority;
//	bool ret = false;
//	int retries = *compaction_retries;
//	enum compact_priority priority = *compact_priority;

//	if (!order)
//		return false;

//	if (compaction_made_progress(compact_result))
//		(*compaction_retries)++;

//	/*
//	 * compaction considers all the zone as desperately out of memory
//	 * so it doesn't really make much sense to retry except when the
//	 * failure could be caused by insufficient priority
//	 */
//	if (compaction_failed(compact_result))
//		goto check_priority;

//	/*
//	 * compaction was skipped because there are not enough order-0 pages
//	 * to work with, so we retry only if it looks like reclaim can help.
//	 */
//	if (compaction_needs_reclaim(compact_result)) {
//		ret = compaction_zonelist_suitable(ac, order, alloc_flags);
//		goto out;
//	}

//	/*
//	 * make sure the compaction wasn't deferred or didn't bail out early
//	 * due to locks contention before we declare that we should give up.
//	 * But the next retry should use a higher priority if allowed, so
//	 * we don't just keep bailing out endlessly.
//	 */
//	if (compaction_withdrawn(compact_result)) {
//		goto check_priority;
//	}

//	/*
//	 * !costly requests are much more important than __GFP_RETRY_MAYFAIL
//	 * costly ones because they are de facto nofail and invoke OOM
//	 * killer to move on while costly can fail and users are ready
//	 * to cope with that. 1/4 retries is rather arbitrary but we
//	 * would need much more detailed feedback from compaction to
//	 * make a better decision.
//	 */
//	if (order > PAGE_ALLOC_COSTLY_ORDER)
//		max_retries /= 4;
//	if (*compaction_retries <= max_retries) {
//		ret = true;
//		goto out;
//	}

//	/*
//	 * Make sure there are attempts at the highest priority if we exhausted
//	 * all retries or failed at the lower priorities.
//	 */
//check_priority:
//	min_priority = (order > PAGE_ALLOC_COSTLY_ORDER) ?
//			MIN_COMPACT_COSTLY_PRIORITY : MIN_COMPACT_PRIORITY;

//	if (*compact_priority > min_priority) {
//		(*compact_priority)--;
//		*compaction_retries = 0;
//		ret = true;
//	}
//out:
//	trace_compact_retry(order, priority, compact_result, retries, max_retries, ret);
//	return ret;
//}
//#else
//static inline struct page *
//__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
//		unsigned int alloc_flags, const struct alloc_context *ac,
//		enum compact_priority prio, enum compact_result *compact_result)
//{
//	*compact_result = COMPACT_SKIPPED;
//	return NULL;
//}

//static inline bool
//should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_flags,
//		     enum compact_result compact_result,
//		     enum compact_priority *compact_priority,
//		     int *compaction_retries)
//{
//	struct zone *zone;
//	struct zoneref *z;

//	if (!order || order > PAGE_ALLOC_COSTLY_ORDER)
//		return false;

//	/*
//	 * There are setups with compaction disabled which would prefer to loop
//	 * inside the allocator rather than hit the oom killer prematurely.
//	 * Let's give them a good hope and keep retrying while the order-0
//	 * watermarks are OK.
//	 */
//	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
//				ac->highest_zoneidx, ac->nodemask) {
//		if (zone_watermark_ok(zone, 0, min_wmark_pages(zone),
//					ac->highest_zoneidx, alloc_flags))
//			return true;
//	}
//	return false;
//}
//#endif /* CONFIG_COMPACTION */

//#ifdef CONFIG_LOCKDEP
//static struct lockdep_map __fs_reclaim_map =
//	STATIC_LOCKDEP_MAP_INIT("fs_reclaim", &__fs_reclaim_map);

//static bool __need_fs_reclaim(gfp_t gfp_mask)
//{
//	gfp_mask = current_gfp_context(gfp_mask);

//	/* no reclaim without waiting on it */
//	if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
//		return false;

//	/* this guy won't enter reclaim */
//	if (current->flags & PF_MEMALLOC)
//		return false;

//	/* We're only interested __GFP_FS allocations for now */
//	if (!(gfp_mask & __GFP_FS))
//		return false;

//	if (gfp_mask & __GFP_NOLOCKDEP)
//		return false;

//	return true;
//}

//void __fs_reclaim_acquire(void)
//{
//	lock_map_acquire(&__fs_reclaim_map);
//}

//void __fs_reclaim_release(void)
//{
//	lock_map_release(&__fs_reclaim_map);
//}

//void fs_reclaim_acquire(gfp_t gfp_mask)
//{
//	if (__need_fs_reclaim(gfp_mask))
//		__fs_reclaim_acquire();
//}
//EXPORT_SYMBOL_GPL(fs_reclaim_acquire);

//void fs_reclaim_release(gfp_t gfp_mask)
//{
//	if (__need_fs_reclaim(gfp_mask))
//		__fs_reclaim_release();
//}
//EXPORT_SYMBOL_GPL(fs_reclaim_release);
//#endif

///* Perform direct synchronous page reclaim */
//static unsigned long
//__perform_reclaim(gfp_t gfp_mask, unsigned int order,
//					const struct alloc_context *ac)
//{
//	unsigned int noreclaim_flag;
//	unsigned long pflags, progress;

//	cond_resched();

//	/* We now go into synchronous reclaim */
//	cpuset_memory_pressure_bump();
//	psi_memstall_enter(&pflags);
//	fs_reclaim_acquire(gfp_mask);
//	noreclaim_flag = memalloc_noreclaim_save();

//	progress = try_to_free_pages(ac->zonelist, order, gfp_mask,
//								ac->nodemask);

//	memalloc_noreclaim_restore(noreclaim_flag);
//	fs_reclaim_release(gfp_mask);
//	psi_memstall_leave(&pflags);

//	cond_resched();

//	return progress;
//}

///* The really slow allocator path where we enter direct reclaim */
//static inline struct page *
//__alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
//		unsigned int alloc_flags, const struct alloc_context *ac,
//		unsigned long *did_some_progress)
//{
//	struct page *page = NULL;
//	bool drained = false;

//	*did_some_progress = __perform_reclaim(gfp_mask, order, ac);
//	if (unlikely(!(*did_some_progress)))
//		return NULL;

//retry:
//	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);

//	/*
//	 * If an allocation failed after direct reclaim, it could be because
//	 * pages are pinned on the per-cpu lists or in high alloc reserves.
//	 * Shrink them and try again
//	 */
//	if (!page && !drained) {
//		unreserve_highatomic_pageblock(ac, false);
//		drain_all_pages(NULL);
//		drained = true;
//		goto retry;
//	}

//	return page;
//}

//static void wake_all_kswapds(unsigned int order, gfp_t gfp_mask,
//			     const struct alloc_context *ac)
//{
//	struct zoneref *z;
//	struct zone *zone;
//	pg_data_t *last_pgdat = NULL;
//	enum zone_type highest_zoneidx = ac->highest_zoneidx;

//	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, highest_zoneidx,
//					ac->nodemask) {
//		if (last_pgdat != zone->zone_pgdat)
//			wakeup_kswapd(zone, gfp_mask, order, highest_zoneidx);
//		last_pgdat = zone->zone_pgdat;
//	}
//}

//static inline unsigned int
//gfp_to_alloc_flags(gfp_t gfp_mask)
//{
//	unsigned int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;

//	/*
//	 * __GFP_HIGH is assumed to be the same as ALLOC_HIGH
//	 * and __GFP_KSWAPD_RECLAIM is assumed to be the same as ALLOC_KSWAPD
//	 * to save two branches.
//	 */
//	BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_HIGH);
//	BUILD_BUG_ON(__GFP_KSWAPD_RECLAIM != (__force gfp_t) ALLOC_KSWAPD);

//	/*
//	 * The caller may dip into page reserves a bit more if the caller
//	 * cannot run direct reclaim, or if the caller has realtime scheduling
//	 * policy or is asking for __GFP_HIGH memory.  GFP_ATOMIC requests will
//	 * set both ALLOC_HARDER (__GFP_ATOMIC) and ALLOC_HIGH (__GFP_HIGH).
//	 */
//	alloc_flags |= (__force int)
//		(gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM));

//	if (gfp_mask & __GFP_ATOMIC) {
//		/*
//		 * Not worth trying to allocate harder for __GFP_NOMEMALLOC even
//		 * if it can't schedule.
//		 */
//		if (!(gfp_mask & __GFP_NOMEMALLOC))
//			alloc_flags |= ALLOC_HARDER;
//		/*
//		 * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the
//		 * comment for __cpuset_node_allowed().
//		 */
//		alloc_flags &= ~ALLOC_CPUSET;
//	} else if (unlikely(rt_task(current)) && !in_interrupt())
//		alloc_flags |= ALLOC_HARDER;

//	alloc_flags = current_alloc_flags(gfp_mask, alloc_flags);

//	return alloc_flags;
//}

//static bool oom_reserves_allowed(struct task_struct *tsk)
//{
//	if (!tsk_is_oom_victim(tsk))
//		return false;

//	/*
//	 * !MMU doesn't have oom reaper so give access to memory reserves
//	 * only to the thread with TIF_MEMDIE set
//	 */
//	if (!IS_ENABLED(CONFIG_MMU) && !test_thread_flag(TIF_MEMDIE))
//		return false;

//	return true;
//}

///*
// * Distinguish requests which really need access to full memory
// * reserves from oom victims which can live with a portion of it
// */
//static inline int __gfp_pfmemalloc_flags(gfp_t gfp_mask)
//{
//	if (unlikely(gfp_mask & __GFP_NOMEMALLOC))
//		return 0;
//	if (gfp_mask & __GFP_MEMALLOC)
//		return ALLOC_NO_WATERMARKS;
//	if (in_serving_softirq() && (current->flags & PF_MEMALLOC))
//		return ALLOC_NO_WATERMARKS;
//	if (!in_interrupt()) {
//		if (current->flags & PF_MEMALLOC)
//			return ALLOC_NO_WATERMARKS;
//		else if (oom_reserves_allowed(current))
//			return ALLOC_OOM;
//	}

//	return 0;
//}

//bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
//{
//	return !!__gfp_pfmemalloc_flags(gfp_mask);
//}

///*
// * Checks whether it makes sense to retry the reclaim to make a forward progress
// * for the given allocation request.
// *
// * We give up when we either have tried MAX_RECLAIM_RETRIES in a row
// * without success, or when we couldn't even meet the watermark if we
// * reclaimed all remaining pages on the LRU lists.
// *
// * Returns true if a retry is viable or false to enter the oom path.
// */
//static inline bool
//should_reclaim_retry(gfp_t gfp_mask, unsigned order,
//		     struct alloc_context *ac, int alloc_flags,
//		     bool did_some_progress, int *no_progress_loops)
//{
//	struct zone *zone;
//	struct zoneref *z;
//	bool ret = false;

//	/*
//	 * Costly allocations might have made a progress but this doesn't mean
//	 * their order will become available due to high fragmentation so
//	 * always increment the no progress counter for them
//	 */
//	if (did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER)
//		*no_progress_loops = 0;
//	else
//		(*no_progress_loops)++;

//	/*
//	 * Make sure we converge to OOM if we cannot make any progress
//	 * several times in the row.
//	 */
//	if (*no_progress_loops > MAX_RECLAIM_RETRIES) {
//		/* Before OOM, exhaust highatomic_reserve */
//		return unreserve_highatomic_pageblock(ac, true);
//	}

//	/*
//	 * Keep reclaiming pages while there is a chance this will lead
//	 * somewhere.  If none of the target zones can satisfy our allocation
//	 * request even if all reclaimable pages are considered then we are
//	 * screwed and have to go OOM.
//	 */
//	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
//				ac->highest_zoneidx, ac->nodemask) {
//		unsigned long available;
//		unsigned long reclaimable;
//		unsigned long min_wmark = min_wmark_pages(zone);
//		bool wmark;

//		available = reclaimable = zone_reclaimable_pages(zone);
//		available += zone_page_state_snapshot(zone, NR_FREE_PAGES);

//		/*
//		 * Would the allocation succeed if we reclaimed all
//		 * reclaimable pages?
//		 */
//		wmark = __zone_watermark_ok(zone, order, min_wmark,
//				ac->highest_zoneidx, alloc_flags, available);
//		trace_reclaim_retry_zone(z, order, reclaimable,
//				available, min_wmark, *no_progress_loops, wmark);
//		if (wmark) {
//			/*
//			 * If we didn't make any progress and have a lot of
//			 * dirty + writeback pages then we should wait for
//			 * an IO to complete to slow down the reclaim and
//			 * prevent from pre mature OOM
//			 */
//			if (!did_some_progress) {
//				unsigned long write_pending;

//				write_pending = zone_page_state_snapshot(zone,
//							NR_ZONE_WRITE_PENDING);

//				if (2 * write_pending > reclaimable) {
//					congestion_wait(BLK_RW_ASYNC, HZ/10);
//					return true;
//				}
//			}

//			ret = true;
//			goto out;
//		}
//	}

//out:
//	/*
//	 * Memory allocation/reclaim might be called from a WQ context and the
//	 * current implementation of the WQ concurrency control doesn't
//	 * recognize that a particular WQ is congested if the worker thread is
//	 * looping without ever sleeping. Therefore we have to do a short sleep
//	 * here rather than calling cond_resched().
//	 */
//	if (current->flags & PF_WQ_WORKER)
//		schedule_timeout_uninterruptible(1);
//	else
//		cond_resched();
//	return ret;
//}

//static inline bool
//check_retry_cpuset(int cpuset_mems_cookie, struct alloc_context *ac)
//{
//	/*
//	 * It's possible that cpuset's mems_allowed and the nodemask from
//	 * mempolicy don't intersect. This should be normally dealt with by
//	 * policy_nodemask(), but it's possible to race with cpuset update in
//	 * such a way the check therein was true, and then it became false
//	 * before we got our cpuset_mems_cookie here.
//	 * This assumes that for all allocations, ac->nodemask can come only
//	 * from MPOL_BIND mempolicy (whose documented semantics is to be ignored
//	 * when it does not intersect with the cpuset restrictions) or the
//	 * caller can deal with a violated nodemask.
//	 */
//	if (cpusets_enabled() && ac->nodemask &&
//			!cpuset_nodemask_valid_mems_allowed(ac->nodemask)) {
//		ac->nodemask = NULL;
//		return true;
//	}

//	/*
//	 * When updating a task's mems_allowed or mempolicy nodemask, it is
//	 * possible to race with parallel threads in such a way that our
//	 * allocation can fail while the mask is being updated. If we are about
//	 * to fail, check if the cpuset changed during allocation and if so,
//	 * retry.
//	 */
//	if (read_mems_allowed_retry(cpuset_mems_cookie))
//		return true;

//	return false;
//}

//static inline struct page *
//__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
//						struct alloc_context *ac)
//{
//	bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM;
//	const bool costly_order = order > PAGE_ALLOC_COSTLY_ORDER;
//	struct page *page = NULL;
//	unsigned int alloc_flags;
//	unsigned long did_some_progress;
//	enum compact_priority compact_priority;
//	enum compact_result compact_result;
//	int compaction_retries;
//	int no_progress_loops;
//	unsigned int cpuset_mems_cookie;
//	int reserve_flags;

//	/*
//	 * We also sanity check to catch abuse of atomic reserves being used by
//	 * callers that are not in atomic context.
//	 */
//	if (WARN_ON_ONCE((gfp_mask & (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)) ==
//				(__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)))
//		gfp_mask &= ~__GFP_ATOMIC;

//retry_cpuset:
//	compaction_retries = 0;
//	no_progress_loops = 0;
//	compact_priority = DEF_COMPACT_PRIORITY;
//	cpuset_mems_cookie = read_mems_allowed_begin();

//	/*
//	 * The fast path uses conservative alloc_flags to succeed only until
//	 * kswapd needs to be woken up, and to avoid the cost of setting up
//	 * alloc_flags precisely. So we do that now.
//	 */
//	alloc_flags = gfp_to_alloc_flags(gfp_mask);

//	/*
//	 * We need to recalculate the starting point for the zonelist iterator
//	 * because we might have used different nodemask in the fast path, or
//	 * there was a cpuset modification and we are retrying - otherwise we
//	 * could end up iterating over non-eligible zones endlessly.
//	 */
//	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
//					ac->highest_zoneidx, ac->nodemask);
//	if (!ac->preferred_zoneref->zone)
//		goto nopage;

//	if (alloc_flags & ALLOC_KSWAPD)
//		wake_all_kswapds(order, gfp_mask, ac);

//	/*
//	 * The adjusted alloc_flags might result in immediate success, so try
//	 * that first
//	 */
//	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
//	if (page)
//		goto got_pg;

//	/*
//	 * For costly allocations, try direct compaction first, as it's likely
//	 * that we have enough base pages and don't need to reclaim. For non-
//	 * movable high-order allocations, do that as well, as compaction will
//	 * try prevent permanent fragmentation by migrating from blocks of the
//	 * same migratetype.
//	 * Don't try this for allocations that are allowed to ignore
//	 * watermarks, as the ALLOC_NO_WATERMARKS attempt didn't yet happen.
//	 */
//	if (can_direct_reclaim &&
//			(costly_order ||
//			   (order > 0 && ac->migratetype != MIGRATE_MOVABLE))
//			&& !gfp_pfmemalloc_allowed(gfp_mask)) {
//		page = __alloc_pages_direct_compact(gfp_mask, order,
//						alloc_flags, ac,
//						INIT_COMPACT_PRIORITY,
//						&compact_result);
//		if (page)
//			goto got_pg;

//		/*
//		 * Checks for costly allocations with __GFP_NORETRY, which
//		 * includes some THP page fault allocations
//		 */
//		if (costly_order && (gfp_mask & __GFP_NORETRY)) {
//			/*
//			 * If allocating entire pageblock(s) and compaction
//			 * failed because all zones are below low watermarks
//			 * or is prohibited because it recently failed at this
//			 * order, fail immediately unless the allocator has
//			 * requested compaction and reclaim retry.
//			 *
//			 * Reclaim is
//			 *  - potentially very expensive because zones are far
//			 *    below their low watermarks or this is part of very
//			 *    bursty high order allocations,
//			 *  - not guaranteed to help because isolate_freepages()
//			 *    may not iterate over freed pages as part of its
//			 *    linear scan, and
//			 *  - unlikely to make entire pageblocks free on its
//			 *    own.
//			 */
//			if (compact_result == COMPACT_SKIPPED ||
//			    compact_result == COMPACT_DEFERRED)
//				goto nopage;

//			/*
//			 * Looks like reclaim/compaction is worth trying, but
//			 * sync compaction could be very expensive, so keep
//			 * using async compaction.
//			 */
//			compact_priority = INIT_COMPACT_PRIORITY;
//		}
//	}

//retry:
//	/* Ensure kswapd doesn't accidentally go to sleep as long as we loop */
//	if (alloc_flags & ALLOC_KSWAPD)
//		wake_all_kswapds(order, gfp_mask, ac);

//	reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
//	if (reserve_flags)
//		alloc_flags = current_alloc_flags(gfp_mask, reserve_flags);

//	/*
//	 * Reset the nodemask and zonelist iterators if memory policies can be
//	 * ignored. These allocations are high priority and system rather than
//	 * user oriented.
//	 */
//	if (!(alloc_flags & ALLOC_CPUSET) || reserve_flags) {
//		ac->nodemask = NULL;
//		ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
//					ac->highest_zoneidx, ac->nodemask);
//	}

//	/* Attempt with potentially adjusted zonelist and alloc_flags */
//	page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
//	if (page)
//		goto got_pg;

//	/* Caller is not willing to reclaim, we can't balance anything */
//	if (!can_direct_reclaim)
//		goto nopage;

//	/* Avoid recursion of direct reclaim */
//	if (current->flags & PF_MEMALLOC)
//		goto nopage;

//	/* Try direct reclaim and then allocating */
//	page = __alloc_pages_direct_reclaim(gfp_mask, order, alloc_flags, ac,
//							&did_some_progress);
//	if (page)
//		goto got_pg;

//	/* Try direct compaction and then allocating */
//	page = __alloc_pages_direct_compact(gfp_mask, order, alloc_flags, ac,
//					compact_priority, &compact_result);
//	if (page)
//		goto got_pg;

//	/* Do not loop if specifically requested */
//	if (gfp_mask & __GFP_NORETRY)
//		goto nopage;

//	/*
//	 * Do not retry costly high order allocations unless they are
//	 * __GFP_RETRY_MAYFAIL
//	 */
//	if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL))
//		goto nopage;

//	if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags,
//				 did_some_progress > 0, &no_progress_loops))
//		goto retry;

//	/*
//	 * It doesn't make any sense to retry for the compaction if the order-0
//	 * reclaim is not able to make any progress because the current
//	 * implementation of the compaction depends on the sufficient amount
//	 * of free memory (see __compaction_suitable)
//	 */
//	if (did_some_progress > 0 &&
//			should_compact_retry(ac, order, alloc_flags,
//				compact_result, &compact_priority,
//				&compaction_retries))
//		goto retry;


//	/* Deal with possible cpuset update races before we start OOM killing */
//	if (check_retry_cpuset(cpuset_mems_cookie, ac))
//		goto retry_cpuset;

//	/* Reclaim has failed us, start killing things */
//	page = __alloc_pages_may_oom(gfp_mask, order, ac, &did_some_progress);
//	if (page)
//		goto got_pg;

//	/* Avoid allocations with no watermarks from looping endlessly */
//	if (tsk_is_oom_victim(current) &&
//	    (alloc_flags & ALLOC_OOM ||
//	     (gfp_mask & __GFP_NOMEMALLOC)))
//		goto nopage;

//	/* Retry as long as the OOM killer is making progress */
//	if (did_some_progress) {
//		no_progress_loops = 0;
//		goto retry;
//	}

//nopage:
//	/* Deal with possible cpuset update races before we fail */
//	if (check_retry_cpuset(cpuset_mems_cookie, ac))
//		goto retry_cpuset;

//	/*
//	 * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
//	 * we always retry
//	 */
//	if (gfp_mask & __GFP_NOFAIL) {
//		/*
//		 * All existing users of the __GFP_NOFAIL are blockable, so warn
//		 * of any new users that actually require GFP_NOWAIT
//		 */
//		if (WARN_ON_ONCE(!can_direct_reclaim))
//			goto fail;

//		/*
//		 * PF_MEMALLOC request from this context is rather bizarre
//		 * because we cannot reclaim anything and only can loop waiting
//		 * for somebody to do a work for us
//		 */
//		WARN_ON_ONCE(current->flags & PF_MEMALLOC);

//		/*
//		 * non failing costly orders are a hard requirement which we
//		 * are not prepared for much so let's warn about these users
//		 * so that we can identify them and convert them to something
//		 * else.
//		 */
//		WARN_ON_ONCE(order > PAGE_ALLOC_COSTLY_ORDER);

//		/*
//		 * Help non-failing allocations by giving them access to memory
//		 * reserves but do not use ALLOC_NO_WATERMARKS because this
//		 * could deplete whole memory reserves which would just make
//		 * the situation worse
//		 */
//		page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_HARDER, ac);
//		if (page)
//			goto got_pg;

//		cond_resched();
//		goto retry;
//	}
//fail:
//	warn_alloc(gfp_mask, ac->nodemask,
//			"page allocation failure: order:%u", order);
//got_pg:
//	return page;
//}

//static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
//		int preferred_nid, nodemask_t *nodemask,
//		struct alloc_context *ac, gfp_t *alloc_mask,
//		unsigned int *alloc_flags)
//{
//	ac->highest_zoneidx = gfp_zone(gfp_mask);
//	ac->zonelist = node_zonelist(preferred_nid, gfp_mask);
//	ac->nodemask = nodemask;
//	ac->migratetype = gfp_migratetype(gfp_mask);

//	if (cpusets_enabled()) {
//		*alloc_mask |= __GFP_HARDWALL;
//		/*
//		 * When we are in the interrupt context, it is irrelevant
//		 * to the current task context. It means that any node ok.
//		 */
//		if (!in_interrupt() && !ac->nodemask)
//			ac->nodemask = &cpuset_current_mems_allowed;
//		else
//			*alloc_flags |= ALLOC_CPUSET;
//	}

//	fs_reclaim_acquire(gfp_mask);
//	fs_reclaim_release(gfp_mask);

//	might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);

//	if (should_fail_alloc_page(gfp_mask, order))
//		return false;

//	*alloc_flags = current_alloc_flags(gfp_mask, *alloc_flags);

//	/* Dirty zone balancing only done in the fast path */
//	ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE);

//	/*
//	 * The preferred zone is used for statistics but crucially it is
//	 * also used as the starting point for the zonelist iterator. It
//	 * may get reset for allocations that ignore memory policies.
//	 */
//	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
//					ac->highest_zoneidx, ac->nodemask);

//	return true;
//}

/*
 * This is the 'heart' of the zoned buddy allocator.
 */
struct page *
__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
							nodemask_t *nodemask)
{
	struct page *page;
//	unsigned int alloc_flags = ALLOC_WMARK_LOW;
//	gfp_t alloc_mask; /* The gfp_t that was actually used for allocation */
//	struct alloc_context ac = { };

//	/*
//	 * There are several places where we assume that the order value is sane
//	 * so bail out early if the request is out of bound.
//	 */
//	if (unlikely(order >= MAX_ORDER)) {
//		WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN));
//		return NULL;
//	}

//	gfp_mask &= gfp_allowed_mask;
//	alloc_mask = gfp_mask;
//	if (!prepare_alloc_pages(gfp_mask, order, preferred_nid, nodemask, &ac, &alloc_mask, &alloc_flags))
//		return NULL;

//	/*
//	 * Forbid the first pass from falling back to types that fragment
//	 * memory until all local zones are considered.
//	 */
//	alloc_flags |= alloc_flags_nofragment(ac.preferred_zoneref->zone, gfp_mask);

//	/* First allocation attempt */
//	page = get_page_from_freelist(alloc_mask, order, alloc_flags, &ac);
//	if (likely(page))
//		goto out;

//	/*
//	 * Apply scoped allocation constraints. This is mainly about GFP_NOFS
//	 * resp. GFP_NOIO which has to be inherited for all allocation requests
//	 * from a particular context which has been marked by
//	 * memalloc_no{fs,io}_{save,restore}.
//	 */
//	alloc_mask = current_gfp_context(gfp_mask);
//	ac.spread_dirty_pages = false;

//	/*
//	 * Restore the original nodemask if it was potentially replaced with
//	 * &cpuset_current_mems_allowed to optimize the fast-path attempt.
//	 */
//	ac.nodemask = nodemask;

//	page = __alloc_pages_slowpath(alloc_mask, order, &ac);

//out:
//	if (memcg_kmem_enabled() && (gfp_mask & __GFP_ACCOUNT) && page &&
//	    unlikely(__memcg_kmem_charge_page(page, gfp_mask, order) != 0)) {
//		__free_pages(page, order);
//		page = NULL;
//	}

//	trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype);
	page = kmalloc(PAGE_SIZE, gfp_mask & ~__GFP_HIGHMEM);

	return page;
}
EXPORT_SYMBOL(__alloc_pages_nodemask);

/*
 * Common helper functions. Never use with __GFP_HIGHMEM because the returned
 * address cannot represent highmem pages. Use alloc_pages and then kmap if
 * you need to access high mem.
 */
unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
{
	struct page *page;

//	page = alloc_pages(gfp_mask & ~__GFP_HIGHMEM, order);
	page = kmalloc(PAGE_SIZE, gfp_mask & ~__GFP_HIGHMEM);
	if (!page)
		return 0;
//	return (unsigned long) page_address(page);
	return (unsigned long) (page);
}
EXPORT_SYMBOL(__get_free_pages);

unsigned long get_zeroed_page(gfp_t gfp_mask)
{
	return __get_free_pages(gfp_mask | __GFP_ZERO, 0);
}
EXPORT_SYMBOL(get_zeroed_page);

//static inline void free_the_page(struct page *page, unsigned int order)
//{
//	if (order == 0)		/* Via pcp? */
//		free_unref_page(page);
//	else
//		__free_pages_ok(page, order, FPI_NONE);
//}

void __free_pages(struct page *page, unsigned int order)
{
//	if (put_page_testzero(page))
//		free_the_page(page, order);
//	else if (!PageHead(page))
//		while (order-- > 0)
//			free_the_page(page + (1 << order), order);
    kfree(page);
}
EXPORT_SYMBOL(__free_pages);

void free_pages(unsigned long addr, unsigned int order)
{
	if (addr != 0) {
//		VM_BUG_ON(!virt_addr_valid((void *)addr));
//		__free_pages(virt_to_page((void *)addr), order);
		kfree((void *)addr);
	}
}

EXPORT_SYMBOL(free_pages);

///*
// * Page Fragment:
// *  An arbitrary-length arbitrary-offset area of memory which resides
// *  within a 0 or higher order page.  Multiple fragments within that page
// *  are individually refcounted, in the page's reference counter.
// *
// * The page_frag functions below provide a simple allocation framework for
// * page fragments.  This is used by the network stack and network device
// * drivers to provide a backing region of memory for use as either an
// * sk_buff->head, or to be used in the "frags" portion of skb_shared_info.
// */
//static struct page *__page_frag_cache_refill(struct page_frag_cache *nc,
//					     gfp_t gfp_mask)
//{
//	struct page *page = NULL;
//	gfp_t gfp = gfp_mask;

//#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
//	gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY |
//		    __GFP_NOMEMALLOC;
//	page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
//				PAGE_FRAG_CACHE_MAX_ORDER);
//	nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE;
//#endif
//	if (unlikely(!page))
//		page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);

//	nc->va = page ? page_address(page) : NULL;

//	return page;
//}

//void __page_frag_cache_drain(struct page *page, unsigned int count)
//{
//	VM_BUG_ON_PAGE(page_ref_count(page) == 0, page);

//	if (page_ref_sub_and_test(page, count))
//		free_the_page(page, compound_order(page));
//}
//EXPORT_SYMBOL(__page_frag_cache_drain);

//void *page_frag_alloc(struct page_frag_cache *nc,
//		      unsigned int fragsz, gfp_t gfp_mask)
//{
//	unsigned int size = PAGE_SIZE;
//	struct page *page;
//	int offset;

//	if (unlikely(!nc->va)) {
//refill:
//		page = __page_frag_cache_refill(nc, gfp_mask);
//		if (!page)
//			return NULL;

//#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
//		/* if size can vary use size else just use PAGE_SIZE */
//		size = nc->size;
//#endif
//		/* Even if we own the page, we do not use atomic_set().
//		 * This would break get_page_unless_zero() users.
//		 */
//		page_ref_add(page, PAGE_FRAG_CACHE_MAX_SIZE);

//		/* reset page count bias and offset to start of new frag */
//		nc->pfmemalloc = page_is_pfmemalloc(page);
//		nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
//		nc->offset = size;
//	}

//	offset = nc->offset - fragsz;
//	if (unlikely(offset < 0)) {
//		page = virt_to_page(nc->va);

//		if (!page_ref_sub_and_test(page, nc->pagecnt_bias))
//			goto refill;

//		if (unlikely(nc->pfmemalloc)) {
//			free_the_page(page, compound_order(page));
//			goto refill;
//		}

//#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
//		/* if size can vary use size else just use PAGE_SIZE */
//		size = nc->size;
//#endif
//		/* OK, page count is 0, we can safely set it */
//		set_page_count(page, PAGE_FRAG_CACHE_MAX_SIZE + 1);

//		/* reset page count bias and offset to start of new frag */
//		nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1;
//		offset = size - fragsz;
//	}

//	nc->pagecnt_bias--;
//	nc->offset = offset;

//	return nc->va + offset;
//}
//EXPORT_SYMBOL(page_frag_alloc);

///*
// * Frees a page fragment allocated out of either a compound or order 0 page.
// */
//void page_frag_free(void *addr)
//{
//	struct page *page = virt_to_head_page(addr);

//	if (unlikely(put_page_testzero(page)))
//		free_the_page(page, compound_order(page));
//}
//EXPORT_SYMBOL(page_frag_free);

//static void *make_alloc_exact(unsigned long addr, unsigned int order,
//		size_t size)
//{
//	if (addr) {
//		unsigned long alloc_end = addr + (PAGE_SIZE << order);
//		unsigned long used = addr + PAGE_ALIGN(size);

//		split_page(virt_to_page((void *)addr), order);
//		while (used < alloc_end) {
//			free_page(used);
//			used += PAGE_SIZE;
//		}
//	}
//	return (void *)addr;
//}

///**
// * alloc_pages_exact - allocate an exact number physically-contiguous pages.
// * @size: the number of bytes to allocate
// * @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
// *
// * This function is similar to alloc_pages(), except that it allocates the
// * minimum number of pages to satisfy the request.  alloc_pages() can only
// * allocate memory in power-of-two pages.
// *
// * This function is also limited by MAX_ORDER.
// *
// * Memory allocated by this function must be released by free_pages_exact().
// *
// * Return: pointer to the allocated area or %NULL in case of error.
// */
//void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
//{
//	unsigned int order = get_order(size);
//	unsigned long addr;

//	if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
//		gfp_mask &= ~__GFP_COMP;

//	addr = __get_free_pages(gfp_mask, order);
//	return make_alloc_exact(addr, order, size);
//}
//EXPORT_SYMBOL(alloc_pages_exact);

///**
// * alloc_pages_exact_nid - allocate an exact number of physically-contiguous
// *			   pages on a node.
// * @nid: the preferred node ID where memory should be allocated
// * @size: the number of bytes to allocate
// * @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
// *
// * Like alloc_pages_exact(), but try to allocate on node nid first before falling
// * back.
// *
// * Return: pointer to the allocated area or %NULL in case of error.
// */
//void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
//{
//	unsigned int order = get_order(size);
//	struct page *p;

//	if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
//		gfp_mask &= ~__GFP_COMP;

//	p = alloc_pages_node(nid, gfp_mask, order);
//	if (!p)
//		return NULL;
//	return make_alloc_exact((unsigned long)page_address(p), order, size);
//}

///**
// * free_pages_exact - release memory allocated via alloc_pages_exact()
// * @virt: the value returned by alloc_pages_exact.
// * @size: size of allocation, same value as passed to alloc_pages_exact().
// *
// * Release the memory allocated by a previous call to alloc_pages_exact.
// */
//void free_pages_exact(void *virt, size_t size)
//{
//	unsigned long addr = (unsigned long)virt;
//	unsigned long end = addr + PAGE_ALIGN(size);

//	while (addr < end) {
//		free_page(addr);
//		addr += PAGE_SIZE;
//	}
//}
//EXPORT_SYMBOL(free_pages_exact);

///**
// * nr_free_zone_pages - count number of pages beyond high watermark
// * @offset: The zone index of the highest zone
// *
// * nr_free_zone_pages() counts the number of pages which are beyond the
// * high watermark within all zones at or below a given zone index.  For each
// * zone, the number of pages is calculated as:
// *
// *     nr_free_zone_pages = managed_pages - high_pages
// *
// * Return: number of pages beyond high watermark.
// */
//static unsigned long nr_free_zone_pages(int offset)
//{
//	struct zoneref *z;
//	struct zone *zone;

//	/* Just pick one node, since fallback list is circular */
//	unsigned long sum = 0;

//	struct zonelist *zonelist = node_zonelist(numa_node_id(), GFP_KERNEL);

//	for_each_zone_zonelist(zone, z, zonelist, offset) {
//		unsigned long size = zone_managed_pages(zone);
//		unsigned long high = high_wmark_pages(zone);
//		if (size > high)
//			sum += size - high;
//	}

//	return sum;
//}

///**
// * nr_free_buffer_pages - count number of pages beyond high watermark
// *
// * nr_free_buffer_pages() counts the number of pages which are beyond the high
// * watermark within ZONE_DMA and ZONE_NORMAL.
// *
// * Return: number of pages beyond high watermark within ZONE_DMA and
// * ZONE_NORMAL.
// */
//unsigned long nr_free_buffer_pages(void)
//{
//	return nr_free_zone_pages(gfp_zone(GFP_USER));
//}
//EXPORT_SYMBOL_GPL(nr_free_buffer_pages);

//static inline void show_node(struct zone *zone)
//{
//	if (IS_ENABLED(CONFIG_NUMA))
//		printk("Node %d ", zone_to_nid(zone));
//}

//long si_mem_available(void)
//{
//	long available;
//	unsigned long pagecache;
//	unsigned long wmark_low = 0;
//	unsigned long pages[NR_LRU_LISTS];
//	unsigned long reclaimable;
//	struct zone *zone;
//	int lru;

//	for (lru = LRU_BASE; lru < NR_LRU_LISTS; lru++)
//		pages[lru] = global_node_page_state(NR_LRU_BASE + lru);

//	for_each_zone(zone)
//		wmark_low += low_wmark_pages(zone);

//	/*
//	 * Estimate the amount of memory available for userspace allocations,
//	 * without causing swapping.
//	 */
//	available = global_zone_page_state(NR_FREE_PAGES) - totalreserve_pages;

//	/*
//	 * Not all the page cache can be freed, otherwise the system will
//	 * start swapping. Assume at least half of the page cache, or the
//	 * low watermark worth of cache, needs to stay.
//	 */
//	pagecache = pages[LRU_ACTIVE_FILE] + pages[LRU_INACTIVE_FILE];
//	pagecache -= min(pagecache / 2, wmark_low);
//	available += pagecache;

//	/*
//	 * Part of the reclaimable slab and other kernel memory consists of
//	 * items that are in use, and cannot be freed. Cap this estimate at the
//	 * low watermark.
//	 */
//	reclaimable = global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B) +
//		global_node_page_state(NR_KERNEL_MISC_RECLAIMABLE);
//	available += reclaimable - min(reclaimable / 2, wmark_low);

//	if (available < 0)
//		available = 0;
//	return available;
//}
//EXPORT_SYMBOL_GPL(si_mem_available);

//void si_meminfo(struct sysinfo *val)
//{
//	val->totalram = totalram_pages();
//	val->sharedram = global_node_page_state(NR_SHMEM);
//	val->freeram = global_zone_page_state(NR_FREE_PAGES);
//	val->bufferram = nr_blockdev_pages();
//	val->totalhigh = totalhigh_pages();
//	val->freehigh = nr_free_highpages();
//	val->mem_unit = PAGE_SIZE;
//}

//EXPORT_SYMBOL(si_meminfo);

//#ifdef CONFIG_NUMA
//void si_meminfo_node(struct sysinfo *val, int nid)
//{
//	int zone_type;		/* needs to be signed */
//	unsigned long managed_pages = 0;
//	unsigned long managed_highpages = 0;
//	unsigned long free_highpages = 0;
//	pg_data_t *pgdat = NODE_DATA(nid);

//	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++)
//		managed_pages += zone_managed_pages(&pgdat->node_zones[zone_type]);
//	val->totalram = managed_pages;
//	val->sharedram = node_page_state(pgdat, NR_SHMEM);
//	val->freeram = sum_zone_node_page_state(nid, NR_FREE_PAGES);
//#ifdef CONFIG_HIGHMEM
//	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
//		struct zone *zone = &pgdat->node_zones[zone_type];

//		if (is_highmem(zone)) {
//			managed_highpages += zone_managed_pages(zone);
//			free_highpages += zone_page_state(zone, NR_FREE_PAGES);
//		}
//	}
//	val->totalhigh = managed_highpages;
//	val->freehigh = free_highpages;
//#else
//	val->totalhigh = managed_highpages;
//	val->freehigh = free_highpages;
//#endif
//	val->mem_unit = PAGE_SIZE;
//}
//#endif

///*
// * Determine whether the node should be displayed or not, depending on whether
// * SHOW_MEM_FILTER_NODES was passed to show_free_areas().
// */
//static bool show_mem_node_skip(unsigned int flags, int nid, nodemask_t *nodemask)
//{
//	if (!(flags & SHOW_MEM_FILTER_NODES))
//		return false;

//	/*
//	 * no node mask - aka implicit memory numa policy. Do not bother with
//	 * the synchronization - read_mems_allowed_begin - because we do not
//	 * have to be precise here.
//	 */
//	if (!nodemask)
//		nodemask = &cpuset_current_mems_allowed;

//	return !node_isset(nid, *nodemask);
//}

//#define K(x) ((x) << (PAGE_SHIFT-10))

//static void show_migration_types(unsigned char type)
//{
//	static const char types[MIGRATE_TYPES] = {
//		[MIGRATE_UNMOVABLE]	= 'U',
//		[MIGRATE_MOVABLE]	= 'M',
//		[MIGRATE_RECLAIMABLE]	= 'E',
//		[MIGRATE_HIGHATOMIC]	= 'H',
//#ifdef CONFIG_CMA
//		[MIGRATE_CMA]		= 'C',
//#endif
//#ifdef CONFIG_MEMORY_ISOLATION
//		[MIGRATE_ISOLATE]	= 'I',
//#endif
//	};
//	char tmp[MIGRATE_TYPES + 1];
//	char *p = tmp;
//	int i;

//	for (i = 0; i < MIGRATE_TYPES; i++) {
//		if (type & (1 << i))
//			*p++ = types[i];
//	}

//	*p = '\0';
//	printk(KERN_CONT "(%s) ", tmp);
//}

///*
// * Show free area list (used inside shift_scroll-lock stuff)
// * We also calculate the percentage fragmentation. We do this by counting the
// * memory on each free list with the exception of the first item on the list.
// *
// * Bits in @filter:
// * SHOW_MEM_FILTER_NODES: suppress nodes that are not allowed by current's
// *   cpuset.
// */
//void show_free_areas(unsigned int filter, nodemask_t *nodemask)
//{
//	unsigned long free_pcp = 0;
//	int cpu;
//	struct zone *zone;
//	pg_data_t *pgdat;

//	for_each_populated_zone(zone) {
//		if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
//			continue;

//		for_each_online_cpu(cpu)
//			free_pcp += per_cpu_ptr(zone->pageset, cpu)->pcp.count;
//	}

//	printk("active_anon:%lu inactive_anon:%lu isolated_anon:%lu\n"
//		" active_file:%lu inactive_file:%lu isolated_file:%lu\n"
//		" unevictable:%lu dirty:%lu writeback:%lu\n"
//		" slab_reclaimable:%lu slab_unreclaimable:%lu\n"
//		" mapped:%lu shmem:%lu pagetables:%lu bounce:%lu\n"
//		" free:%lu free_pcp:%lu free_cma:%lu\n",
//		global_node_page_state(NR_ACTIVE_ANON),
//		global_node_page_state(NR_INACTIVE_ANON),
//		global_node_page_state(NR_ISOLATED_ANON),
//		global_node_page_state(NR_ACTIVE_FILE),
//		global_node_page_state(NR_INACTIVE_FILE),
//		global_node_page_state(NR_ISOLATED_FILE),
//		global_node_page_state(NR_UNEVICTABLE),
//		global_node_page_state(NR_FILE_DIRTY),
//		global_node_page_state(NR_WRITEBACK),
//		global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B),
//		global_node_page_state_pages(NR_SLAB_UNRECLAIMABLE_B),
//		global_node_page_state(NR_FILE_MAPPED),
//		global_node_page_state(NR_SHMEM),
//		global_zone_page_state(NR_PAGETABLE),
//		global_zone_page_state(NR_BOUNCE),
//		global_zone_page_state(NR_FREE_PAGES),
//		free_pcp,
//		global_zone_page_state(NR_FREE_CMA_PAGES));

//	for_each_online_pgdat(pgdat) {
//		if (show_mem_node_skip(filter, pgdat->node_id, nodemask))
//			continue;

//		printk("Node %d"
//			" active_anon:%lukB"
//			" inactive_anon:%lukB"
//			" active_file:%lukB"
//			" inactive_file:%lukB"
//			" unevictable:%lukB"
//			" isolated(anon):%lukB"
//			" isolated(file):%lukB"
//			" mapped:%lukB"
//			" dirty:%lukB"
//			" writeback:%lukB"
//			" shmem:%lukB"
//#ifdef CONFIG_TRANSPARENT_HUGEPAGE
//			" shmem_thp: %lukB"
//			" shmem_pmdmapped: %lukB"
//			" anon_thp: %lukB"
//#endif
//			" writeback_tmp:%lukB"
//			" kernel_stack:%lukB"
//#ifdef CONFIG_SHADOW_CALL_STACK
//			" shadow_call_stack:%lukB"
//#endif
//			" all_unreclaimable? %s"
//			"\n",
//			pgdat->node_id,
//			K(node_page_state(pgdat, NR_ACTIVE_ANON)),
//			K(node_page_state(pgdat, NR_INACTIVE_ANON)),
//			K(node_page_state(pgdat, NR_ACTIVE_FILE)),
//			K(node_page_state(pgdat, NR_INACTIVE_FILE)),
//			K(node_page_state(pgdat, NR_UNEVICTABLE)),
//			K(node_page_state(pgdat, NR_ISOLATED_ANON)),
//			K(node_page_state(pgdat, NR_ISOLATED_FILE)),
//			K(node_page_state(pgdat, NR_FILE_MAPPED)),
//			K(node_page_state(pgdat, NR_FILE_DIRTY)),
//			K(node_page_state(pgdat, NR_WRITEBACK)),
//			K(node_page_state(pgdat, NR_SHMEM)),
//#ifdef CONFIG_TRANSPARENT_HUGEPAGE
//			K(node_page_state(pgdat, NR_SHMEM_THPS) * HPAGE_PMD_NR),
//			K(node_page_state(pgdat, NR_SHMEM_PMDMAPPED)
//					* HPAGE_PMD_NR),
//			K(node_page_state(pgdat, NR_ANON_THPS) * HPAGE_PMD_NR),
//#endif
//			K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
//			node_page_state(pgdat, NR_KERNEL_STACK_KB),
//#ifdef CONFIG_SHADOW_CALL_STACK
//			node_page_state(pgdat, NR_KERNEL_SCS_KB),
//#endif
//			pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES ?
//				"yes" : "no");
//	}

//	for_each_populated_zone(zone) {
//		int i;

//		if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
//			continue;

//		free_pcp = 0;
//		for_each_online_cpu(cpu)
//			free_pcp += per_cpu_ptr(zone->pageset, cpu)->pcp.count;

//		show_node(zone);
//		printk(KERN_CONT
//			"%s"
//			" free:%lukB"
//			" min:%lukB"
//			" low:%lukB"
//			" high:%lukB"
//			" reserved_highatomic:%luKB"
//			" active_anon:%lukB"
//			" inactive_anon:%lukB"
//			" active_file:%lukB"
//			" inactive_file:%lukB"
//			" unevictable:%lukB"
//			" writepending:%lukB"
//			" present:%lukB"
//			" managed:%lukB"
//			" mlocked:%lukB"
//			" pagetables:%lukB"
//			" bounce:%lukB"
//			" free_pcp:%lukB"
//			" local_pcp:%ukB"
//			" free_cma:%lukB"
//			"\n",
//			zone->name,
//			K(zone_page_state(zone, NR_FREE_PAGES)),
//			K(min_wmark_pages(zone)),
//			K(low_wmark_pages(zone)),
//			K(high_wmark_pages(zone)),
//			K(zone->nr_reserved_highatomic),
//			K(zone_page_state(zone, NR_ZONE_ACTIVE_ANON)),
//			K(zone_page_state(zone, NR_ZONE_INACTIVE_ANON)),
//			K(zone_page_state(zone, NR_ZONE_ACTIVE_FILE)),
//			K(zone_page_state(zone, NR_ZONE_INACTIVE_FILE)),
//			K(zone_page_state(zone, NR_ZONE_UNEVICTABLE)),
//			K(zone_page_state(zone, NR_ZONE_WRITE_PENDING)),
//			K(zone->present_pages),
//			K(zone_managed_pages(zone)),
//			K(zone_page_state(zone, NR_MLOCK)),
//			K(zone_page_state(zone, NR_PAGETABLE)),
//			K(zone_page_state(zone, NR_BOUNCE)),
//			K(free_pcp),
//			K(this_cpu_read(zone->pageset->pcp.count)),
//			K(zone_page_state(zone, NR_FREE_CMA_PAGES)));
//		printk("lowmem_reserve[]:");
//		for (i = 0; i < MAX_NR_ZONES; i++)
//			printk(KERN_CONT " %ld", zone->lowmem_reserve[i]);
//		printk(KERN_CONT "\n");
//	}

//	for_each_populated_zone(zone) {
//		unsigned int order;
//		unsigned long nr[MAX_ORDER], flags, total = 0;
//		unsigned char types[MAX_ORDER];

//		if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
//			continue;
//		show_node(zone);
//		printk(KERN_CONT "%s: ", zone->name);

//		spin_lock_irqsave(&zone->lock, flags);
//		for (order = 0; order < MAX_ORDER; order++) {
//			struct free_area *area = &zone->free_area[order];
//			int type;

//			nr[order] = area->nr_free;
//			total += nr[order] << order;

//			types[order] = 0;
//			for (type = 0; type < MIGRATE_TYPES; type++) {
//				if (!free_area_empty(area, type))
//					types[order] |= 1 << type;
//			}
//		}
//		spin_unlock_irqrestore(&zone->lock, flags);
//		for (order = 0; order < MAX_ORDER; order++) {
//			printk(KERN_CONT "%lu*%lukB ",
//			       nr[order], K(1UL) << order);
//			if (nr[order])
//				show_migration_types(types[order]);
//		}
//		printk(KERN_CONT "= %lukB\n", K(total));
//	}

//	hugetlb_show_meminfo();

//	printk("%ld total pagecache pages\n", global_node_page_state(NR_FILE_PAGES));

//	show_swap_cache_info();
//}

//static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
//{
//	zoneref->zone = zone;
//	zoneref->zone_idx = zone_idx(zone);
//}

///*
// * Builds allocation fallback zone lists.
// *
// * Add all populated zones of a node to the zonelist.
// */
//static int build_zonerefs_node(pg_data_t *pgdat, struct zoneref *zonerefs)
//{
//	struct zone *zone;
//	enum zone_type zone_type = MAX_NR_ZONES;
//	int nr_zones = 0;

//	do {
//		zone_type--;
//		zone = pgdat->node_zones + zone_type;
//		if (managed_zone(zone)) {
//			zoneref_set_zone(zone, &zonerefs[nr_zones++]);
//			check_highest_zone(zone_type);
//		}
//	} while (zone_type);

//	return nr_zones;
//}

//#ifdef CONFIG_NUMA

//static int __parse_numa_zonelist_order(char *s)
//{
//	/*
//	 * We used to support different zonlists modes but they turned
//	 * out to be just not useful. Let's keep the warning in place
//	 * if somebody still use the cmd line parameter so that we do
//	 * not fail it silently
//	 */
//	if (!(*s == 'd' || *s == 'D' || *s == 'n' || *s == 'N')) {
//		pr_warn("Ignoring unsupported numa_zonelist_order value:  %s\n", s);
//		return -EINVAL;
//	}
//	return 0;
//}

//char numa_zonelist_order[] = "Node";

///*
// * sysctl handler for numa_zonelist_order
// */
//int numa_zonelist_order_handler(struct ctl_table *table, int write,
//		void *buffer, size_t *length, loff_t *ppos)
//{
//	if (write)
//		return __parse_numa_zonelist_order(buffer);
//	return proc_dostring(table, write, buffer, length, ppos);
//}


//#define MAX_NODE_LOAD (nr_online_nodes)
//static int node_load[MAX_NUMNODES];

///**
// * find_next_best_node - find the next node that should appear in a given node's fallback list
// * @node: node whose fallback list we're appending
// * @used_node_mask: nodemask_t of already used nodes
// *
// * We use a number of factors to determine which is the next node that should
// * appear on a given node's fallback list.  The node should not have appeared
// * already in @node's fallback list, and it should be the next closest node
// * according to the distance array (which contains arbitrary distance values
// * from each node to each node in the system), and should also prefer nodes
// * with no CPUs, since presumably they'll have very little allocation pressure
// * on them otherwise.
// *
// * Return: node id of the found node or %NUMA_NO_NODE if no node is found.
// */
//static int find_next_best_node(int node, nodemask_t *used_node_mask)
//{
//	int n, val;
//	int min_val = INT_MAX;
//	int best_node = NUMA_NO_NODE;

//	/* Use the local node if we haven't already */
//	if (!node_isset(node, *used_node_mask)) {
//		node_set(node, *used_node_mask);
//		return node;
//	}

//	for_each_node_state(n, N_MEMORY) {

//		/* Don't want a node to appear more than once */
//		if (node_isset(n, *used_node_mask))
//			continue;

//		/* Use the distance array to find the distance */
//		val = node_distance(node, n);

//		/* Penalize nodes under us ("prefer the next node") */
//		val += (n < node);

//		/* Give preference to headless and unused nodes */
//		if (!cpumask_empty(cpumask_of_node(n)))
//			val += PENALTY_FOR_NODE_WITH_CPUS;

//		/* Slight preference for less loaded node */
//		val *= (MAX_NODE_LOAD*MAX_NUMNODES);
//		val += node_load[n];

//		if (val < min_val) {
//			min_val = val;
//			best_node = n;
//		}
//	}

//	if (best_node >= 0)
//		node_set(best_node, *used_node_mask);

//	return best_node;
//}


///*
// * Build zonelists ordered by node and zones within node.
// * This results in maximum locality--normal zone overflows into local
// * DMA zone, if any--but risks exhausting DMA zone.
// */
//static void build_zonelists_in_node_order(pg_data_t *pgdat, int *node_order,
//		unsigned nr_nodes)
//{
//	struct zoneref *zonerefs;
//	int i;

//	zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;

//	for (i = 0; i < nr_nodes; i++) {
//		int nr_zones;

//		pg_data_t *node = NODE_DATA(node_order[i]);

//		nr_zones = build_zonerefs_node(node, zonerefs);
//		zonerefs += nr_zones;
//	}
//	zonerefs->zone = NULL;
//	zonerefs->zone_idx = 0;
//}

///*
// * Build gfp_thisnode zonelists
// */
//static void build_thisnode_zonelists(pg_data_t *pgdat)
//{
//	struct zoneref *zonerefs;
//	int nr_zones;

//	zonerefs = pgdat->node_zonelists[ZONELIST_NOFALLBACK]._zonerefs;
//	nr_zones = build_zonerefs_node(pgdat, zonerefs);
//	zonerefs += nr_zones;
//	zonerefs->zone = NULL;
//	zonerefs->zone_idx = 0;
//}

///*
// * Build zonelists ordered by zone and nodes within zones.
// * This results in conserving DMA zone[s] until all Normal memory is
// * exhausted, but results in overflowing to remote node while memory
// * may still exist in local DMA zone.
// */

//static void build_zonelists(pg_data_t *pgdat)
//{
//	static int node_order[MAX_NUMNODES];
//	int node, load, nr_nodes = 0;
//	nodemask_t used_mask = NODE_MASK_NONE;
//	int local_node, prev_node;

//	/* NUMA-aware ordering of nodes */
//	local_node = pgdat->node_id;
//	load = nr_online_nodes;
//	prev_node = local_node;

//	memset(node_order, 0, sizeof(node_order));
//	while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
//		/*
//		 * We don't want to pressure a particular node.
//		 * So adding penalty to the first node in same
//		 * distance group to make it round-robin.
//		 */
//		if (node_distance(local_node, node) !=
//		    node_distance(local_node, prev_node))
//			node_load[node] = load;

//		node_order[nr_nodes++] = node;
//		prev_node = node;
//		load--;
//	}

//	build_zonelists_in_node_order(pgdat, node_order, nr_nodes);
//	build_thisnode_zonelists(pgdat);
//}

//#ifdef CONFIG_HAVE_MEMORYLESS_NODES
///*
// * Return node id of node used for "local" allocations.
// * I.e., first node id of first zone in arg node's generic zonelist.
// * Used for initializing percpu 'numa_mem', which is used primarily
// * for kernel allocations, so use GFP_KERNEL flags to locate zonelist.
// */
//int local_memory_node(int node)
//{
//	struct zoneref *z;

//	z = first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
//				   gfp_zone(GFP_KERNEL),
//				   NULL);
//	return zone_to_nid(z->zone);
//}
//#endif

//static void setup_min_unmapped_ratio(void);
//static void setup_min_slab_ratio(void);
//#else	/* CONFIG_NUMA */

//static void build_zonelists(pg_data_t *pgdat)
//{
//	int node, local_node;
//	struct zoneref *zonerefs;
//	int nr_zones;

//	local_node = pgdat->node_id;

//	zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
//	nr_zones = build_zonerefs_node(pgdat, zonerefs);
//	zonerefs += nr_zones;

//	/*
//	 * Now we build the zonelist so that it contains the zones
//	 * of all the other nodes.
//	 * We don't want to pressure a particular node, so when
//	 * building the zones for node N, we make sure that the
//	 * zones coming right after the local ones are those from
//	 * node N+1 (modulo N)
//	 */
//	for (node = local_node + 1; node < MAX_NUMNODES; node++) {
//		if (!node_online(node))
//			continue;
//		nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
//		zonerefs += nr_zones;
//	}
//	for (node = 0; node < local_node; node++) {
//		if (!node_online(node))
//			continue;
//		nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
//		zonerefs += nr_zones;
//	}

//	zonerefs->zone = NULL;
//	zonerefs->zone_idx = 0;
//}

//#endif	/* CONFIG_NUMA */

///*
// * Boot pageset table. One per cpu which is going to be used for all
// * zones and all nodes. The parameters will be set in such a way
// * that an item put on a list will immediately be handed over to
// * the buddy list. This is safe since pageset manipulation is done
// * with interrupts disabled.
// *
// * The boot_pagesets must be kept even after bootup is complete for
// * unused processors and/or zones. They do play a role for bootstrapping
// * hotplugged processors.
// *
// * zoneinfo_show() and maybe other functions do
// * not check if the processor is online before following the pageset pointer.
// * Other parts of the kernel may not check if the zone is available.
// */
//static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch);
//static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset);
//static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);

//static void __build_all_zonelists(void *data)
//{
//	int nid;
//	int __maybe_unused cpu;
//	pg_data_t *self = data;
//	static DEFINE_SPINLOCK(lock);

//	spin_lock(&lock);

//#ifdef CONFIG_NUMA
//	memset(node_load, 0, sizeof(node_load));
//#endif

//	/*
//	 * This node is hotadded and no memory is yet present.   So just
//	 * building zonelists is fine - no need to touch other nodes.
//	 */
//	if (self && !node_online(self->node_id)) {
//		build_zonelists(self);
//	} else {
//		for_each_online_node(nid) {
//			pg_data_t *pgdat = NODE_DATA(nid);

//			build_zonelists(pgdat);
//		}

//#ifdef CONFIG_HAVE_MEMORYLESS_NODES
//		/*
//		 * We now know the "local memory node" for each node--
//		 * i.e., the node of the first zone in the generic zonelist.
//		 * Set up numa_mem percpu variable for on-line cpus.  During
//		 * boot, only the boot cpu should be on-line;  we'll init the
//		 * secondary cpus' numa_mem as they come on-line.  During
//		 * node/memory hotplug, we'll fixup all on-line cpus.
//		 */
//		for_each_online_cpu(cpu)
//			set_cpu_numa_mem(cpu, local_memory_node(cpu_to_node(cpu)));
//#endif
//	}

//	spin_unlock(&lock);
//}

//static noinline void __init
//build_all_zonelists_init(void)
//{
//	int cpu;

//	__build_all_zonelists(NULL);

//	/*
//	 * Initialize the boot_pagesets that are going to be used
//	 * for bootstrapping processors. The real pagesets for
//	 * each zone will be allocated later when the per cpu
//	 * allocator is available.
//	 *
//	 * boot_pagesets are used also for bootstrapping offline
//	 * cpus if the system is already booted because the pagesets
//	 * are needed to initialize allocators on a specific cpu too.
//	 * F.e. the percpu allocator needs the page allocator which
//	 * needs the percpu allocator in order to allocate its pagesets
//	 * (a chicken-egg dilemma).
//	 */
//	for_each_possible_cpu(cpu)
//		setup_pageset(&per_cpu(boot_pageset, cpu), 0);

//	mminit_verify_zonelist();
//	cpuset_init_current_mems_allowed();
//}

///*
// * unless system_state == SYSTEM_BOOTING.
// *
// * __ref due to call of __init annotated helper build_all_zonelists_init
// * [protected by SYSTEM_BOOTING].
// */
//void __ref build_all_zonelists(pg_data_t *pgdat)
//{
//	unsigned long vm_total_pages;

//	if (system_state == SYSTEM_BOOTING) {
//		build_all_zonelists_init();
//	} else {
//		__build_all_zonelists(pgdat);
//		/* cpuset refresh routine should be here */
//	}
//	/* Get the number of free pages beyond high watermark in all zones. */
//	vm_total_pages = nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
//	/*
//	 * Disable grouping by mobility if the number of pages in the
//	 * system is too low to allow the mechanism to work. It would be
//	 * more accurate, but expensive to check per-zone. This check is
//	 * made on memory-hotadd so a system can start with mobility
//	 * disabled and enable it later
//	 */
//	if (vm_total_pages < (pageblock_nr_pages * MIGRATE_TYPES))
//		page_group_by_mobility_disabled = 1;
//	else
//		page_group_by_mobility_disabled = 0;

//	pr_info("Built %u zonelists, mobility grouping %s.  Total pages: %ld\n",
//		nr_online_nodes,
//		page_group_by_mobility_disabled ? "off" : "on",
//		vm_total_pages);
//#ifdef CONFIG_NUMA
//	pr_info("Policy zone: %s\n", zone_names[policy_zone]);
//#endif
//}

///* If zone is ZONE_MOVABLE but memory is mirrored, it is an overlapped init */
//static bool __meminit
//overlap_memmap_init(unsigned long zone, unsigned long *pfn)
//{
//	static struct memblock_region *r;

//	if (mirrored_kernelcore && zone == ZONE_MOVABLE) {
//		if (!r || *pfn >= memblock_region_memory_end_pfn(r)) {
//			for_each_mem_region(r) {
//				if (*pfn < memblock_region_memory_end_pfn(r))
//					break;
//			}
//		}
//		if (*pfn >= memblock_region_memory_base_pfn(r) &&
//		    memblock_is_mirror(r)) {
//			*pfn = memblock_region_memory_end_pfn(r);
//			return true;
//		}
//	}
//	return false;
//}

///*
// * Initially all pages are reserved - free ones are freed
// * up by memblock_free_all() once the early boot process is
// * done. Non-atomic initialization, single-pass.
// *
// * All aligned pageblocks are initialized to the specified migratetype
// * (usually MIGRATE_MOVABLE). Besides setting the migratetype, no related
// * zone stats (e.g., nr_isolate_pageblock) are touched.
// */
//void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
//		unsigned long start_pfn, unsigned long zone_end_pfn,
//		enum meminit_context context,
//		struct vmem_altmap *altmap, int migratetype)
//{
//	unsigned long pfn, end_pfn = start_pfn + size;
//	struct page *page;

//	if (highest_memmap_pfn < end_pfn - 1)
//		highest_memmap_pfn = end_pfn - 1;

//#ifdef CONFIG_ZONE_DEVICE
//	/*
//	 * Honor reservation requested by the driver for this ZONE_DEVICE
//	 * memory. We limit the total number of pages to initialize to just
//	 * those that might contain the memory mapping. We will defer the
//	 * ZONE_DEVICE page initialization until after we have released
//	 * the hotplug lock.
//	 */
//	if (zone == ZONE_DEVICE) {
//		if (!altmap)
//			return;

//		if (start_pfn == altmap->base_pfn)
//			start_pfn += altmap->reserve;
//		end_pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
//	}
//#endif

//	for (pfn = start_pfn; pfn < end_pfn; ) {
//		/*
//		 * There can be holes in boot-time mem_map[]s handed to this
//		 * function.  They do not exist on hotplugged memory.
//		 */
//		if (context == MEMINIT_EARLY) {
//			if (overlap_memmap_init(zone, &pfn))
//				continue;
//			if (defer_init(nid, pfn, zone_end_pfn))
//				break;
//		}

//		page = pfn_to_page(pfn);
//		__init_single_page(page, pfn, zone, nid);
//		if (context == MEMINIT_HOTPLUG)
//			__SetPageReserved(page);

//		/*
//		 * Usually, we want to mark the pageblock MIGRATE_MOVABLE,
//		 * such that unmovable allocations won't be scattered all
//		 * over the place during system boot.
//		 */
//		if (IS_ALIGNED(pfn, pageblock_nr_pages)) {
//			set_pageblock_migratetype(page, migratetype);
//			cond_resched();
//		}
//		pfn++;
//	}
//}

//#ifdef CONFIG_ZONE_DEVICE
//void __ref memmap_init_zone_device(struct zone *zone,
//				   unsigned long start_pfn,
//				   unsigned long nr_pages,
//				   struct dev_pagemap *pgmap)
//{
//	unsigned long pfn, end_pfn = start_pfn + nr_pages;
//	struct pglist_data *pgdat = zone->zone_pgdat;
//	struct vmem_altmap *altmap = pgmap_altmap(pgmap);
//	unsigned long zone_idx = zone_idx(zone);
//	unsigned long start = jiffies;
//	int nid = pgdat->node_id;

//	if (WARN_ON_ONCE(!pgmap || zone_idx(zone) != ZONE_DEVICE))
//		return;

//	/*
//	 * The call to memmap_init_zone should have already taken care
//	 * of the pages reserved for the memmap, so we can just jump to
//	 * the end of that region and start processing the device pages.
//	 */
//	if (altmap) {
//		start_pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
//		nr_pages = end_pfn - start_pfn;
//	}

//	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
//		struct page *page = pfn_to_page(pfn);

//		__init_single_page(page, pfn, zone_idx, nid);

//		/*
//		 * Mark page reserved as it will need to wait for onlining
//		 * phase for it to be fully associated with a zone.
//		 *
//		 * We can use the non-atomic __set_bit operation for setting
//		 * the flag as we are still initializing the pages.
//		 */
//		__SetPageReserved(page);

//		/*
//		 * ZONE_DEVICE pages union ->lru with a ->pgmap back pointer
//		 * and zone_device_data.  It is a bug if a ZONE_DEVICE page is
//		 * ever freed or placed on a driver-private list.
//		 */
//		page->pgmap = pgmap;
//		page->zone_device_data = NULL;

//		/*
//		 * Mark the block movable so that blocks are reserved for
//		 * movable at startup. This will force kernel allocations
//		 * to reserve their blocks rather than leaking throughout
//		 * the address space during boot when many long-lived
//		 * kernel allocations are made.
//		 *
//		 * Please note that MEMINIT_HOTPLUG path doesn't clear memmap
//		 * because this is done early in section_activate()
//		 */
//		if (IS_ALIGNED(pfn, pageblock_nr_pages)) {
//			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
//			cond_resched();
//		}
//	}

//	pr_info("%s initialised %lu pages in %ums\n", __func__,
//		nr_pages, jiffies_to_msecs(jiffies - start));
//}

//#endif
//static void __meminit zone_init_free_lists(struct zone *zone)
//{
//	unsigned int order, t;
//	for_each_migratetype_order(order, t) {
//		INIT_LIST_HEAD(&zone->free_area[order].free_list[t]);
//		zone->free_area[order].nr_free = 0;
//	}
//}

//#if !defined(CONFIG_FLAT_NODE_MEM_MAP)
///*
// * Only struct pages that correspond to ranges defined by memblock.memory
// * are zeroed and initialized by going through __init_single_page() during
// * memmap_init_zone().
// *
// * But, there could be struct pages that correspond to holes in
// * memblock.memory. This can happen because of the following reasons:
// * - physical memory bank size is not necessarily the exact multiple of the
// *   arbitrary section size
// * - early reserved memory may not be listed in memblock.memory
// * - memory layouts defined with memmap= kernel parameter may not align
// *   nicely with memmap sections
// *
// * Explicitly initialize those struct pages so that:
// * - PG_Reserved is set
// * - zone and node links point to zone and node that span the page if the
// *   hole is in the middle of a zone
// * - zone and node links point to adjacent zone/node if the hole falls on
// *   the zone boundary; the pages in such holes will be prepended to the
// *   zone/node above the hole except for the trailing pages in the last
// *   section that will be appended to the zone/node below.
// */
//static u64 __meminit init_unavailable_range(unsigned long spfn,
//					    unsigned long epfn,
//					    int zone, int node)
//{
//	unsigned long pfn;
//	u64 pgcnt = 0;

//	for (pfn = spfn; pfn < epfn; pfn++) {
//		if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) {
//			pfn = ALIGN_DOWN(pfn, pageblock_nr_pages)
//				+ pageblock_nr_pages - 1;
//			continue;
//		}
//		__init_single_page(pfn_to_page(pfn), pfn, zone, node);
//		__SetPageReserved(pfn_to_page(pfn));
//		pgcnt++;
//	}

//	return pgcnt;
//}
//#else
//static inline u64 init_unavailable_range(unsigned long spfn, unsigned long epfn,
//					 int zone, int node)
//{
//	return 0;
//}
//#endif

//void __meminit __weak memmap_init(unsigned long size, int nid,
//				  unsigned long zone,
//				  unsigned long range_start_pfn)
//{
//	static unsigned long hole_pfn;
//	unsigned long start_pfn, end_pfn;
//	unsigned long range_end_pfn = range_start_pfn + size;
//	int i;
//	u64 pgcnt = 0;

//	for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
//		start_pfn = clamp(start_pfn, range_start_pfn, range_end_pfn);
//		end_pfn = clamp(end_pfn, range_start_pfn, range_end_pfn);

//		if (end_pfn > start_pfn) {
//			size = end_pfn - start_pfn;
//			memmap_init_zone(size, nid, zone, start_pfn, range_end_pfn,
//					 MEMINIT_EARLY, NULL, MIGRATE_MOVABLE);
//		}

//		if (hole_pfn < start_pfn)
//			pgcnt += init_unavailable_range(hole_pfn, start_pfn,
//							zone, nid);
//		hole_pfn = end_pfn;
//	}

//#ifdef CONFIG_SPARSEMEM
//	/*
//	 * Initialize the hole in the range [zone_end_pfn, section_end].
//	 * If zone boundary falls in the middle of a section, this hole
//	 * will be re-initialized during the call to this function for the
//	 * higher zone.
//	 */
//	end_pfn = round_up(range_end_pfn, PAGES_PER_SECTION);
//	if (hole_pfn < end_pfn)
//		pgcnt += init_unavailable_range(hole_pfn, end_pfn,
//						zone, nid);
//#endif

//	if (pgcnt)
//		pr_info("  %s zone: %llu pages in unavailable ranges\n",
//			zone_names[zone], pgcnt);
//}

//static int zone_batchsize(struct zone *zone)
//{
//#ifdef CONFIG_MMU
//	int batch;

//	/*
//	 * The per-cpu-pages pools are set to around 1000th of the
//	 * size of the zone.
//	 */
//	batch = zone_managed_pages(zone) / 1024;
//	/* But no more than a meg. */
//	if (batch * PAGE_SIZE > 1024 * 1024)
//		batch = (1024 * 1024) / PAGE_SIZE;
//	batch /= 4;		/* We effectively *= 4 below */
//	if (batch < 1)
//		batch = 1;

//	/*
//	 * Clamp the batch to a 2^n - 1 value. Having a power
//	 * of 2 value was found to be more likely to have
//	 * suboptimal cache aliasing properties in some cases.
//	 *
//	 * For example if 2 tasks are alternately allocating
//	 * batches of pages, one task can end up with a lot
//	 * of pages of one half of the possible page colors
//	 * and the other with pages of the other colors.
//	 */
//	batch = rounddown_pow_of_two(batch + batch/2) - 1;

//	return batch;

//#else
//	/* The deferral and batching of frees should be suppressed under NOMMU
//	 * conditions.
//	 *
//	 * The problem is that NOMMU needs to be able to allocate large chunks
//	 * of contiguous memory as there's no hardware page translation to
//	 * assemble apparent contiguous memory from discontiguous pages.
//	 *
//	 * Queueing large contiguous runs of pages for batching, however,
//	 * causes the pages to actually be freed in smaller chunks.  As there
//	 * can be a significant delay between the individual batches being
//	 * recycled, this leads to the once large chunks of space being
//	 * fragmented and becoming unavailable for high-order allocations.
//	 */
//	return 0;
//#endif
//}

///*
// * pcp->high and pcp->batch values are related and dependent on one another:
// * ->batch must never be higher then ->high.
// * The following function updates them in a safe manner without read side
// * locking.
// *
// * Any new users of pcp->batch and pcp->high should ensure they can cope with
// * those fields changing asynchronously (acording to the above rule).
// *
// * mutex_is_locked(&pcp_batch_high_lock) required when calling this function
// * outside of boot time (or some other assurance that no concurrent updaters
// * exist).
// */
//static void pageset_update(struct per_cpu_pages *pcp, unsigned long high,
//		unsigned long batch)
//{
//       /* start with a fail safe value for batch */
//	pcp->batch = 1;
//	smp_wmb();

//       /* Update high, then batch, in order */
//	pcp->high = high;
//	smp_wmb();

//	pcp->batch = batch;
//}

///* a companion to pageset_set_high() */
//static void pageset_set_batch(struct per_cpu_pageset *p, unsigned long batch)
//{
//	pageset_update(&p->pcp, 6 * batch, max(1UL, 1 * batch));
//}

//static void pageset_init(struct per_cpu_pageset *p)
//{
//	struct per_cpu_pages *pcp;
//	int migratetype;

//	memset(p, 0, sizeof(*p));

//	pcp = &p->pcp;
//	for (migratetype = 0; migratetype < MIGRATE_PCPTYPES; migratetype++)
//		INIT_LIST_HEAD(&pcp->lists[migratetype]);
//}

//static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch)
//{
//	pageset_init(p);
//	pageset_set_batch(p, batch);
//}

///*
// * pageset_set_high() sets the high water mark for hot per_cpu_pagelist
// * to the value high for the pageset p.
// */
//static void pageset_set_high(struct per_cpu_pageset *p,
//				unsigned long high)
//{
//	unsigned long batch = max(1UL, high / 4);
//	if ((high / 4) > (PAGE_SHIFT * 8))
//		batch = PAGE_SHIFT * 8;

//	pageset_update(&p->pcp, high, batch);
//}

//static void pageset_set_high_and_batch(struct zone *zone,
//				       struct per_cpu_pageset *pcp)
//{
//	if (percpu_pagelist_fraction)
//		pageset_set_high(pcp,
//			(zone_managed_pages(zone) /
//				percpu_pagelist_fraction));
//	else
//		pageset_set_batch(pcp, zone_batchsize(zone));
//}

//static void __meminit zone_pageset_init(struct zone *zone, int cpu)
//{
//	struct per_cpu_pageset *pcp = per_cpu_ptr(zone->pageset, cpu);

//	pageset_init(pcp);
//	pageset_set_high_and_batch(zone, pcp);
//}

//void __meminit setup_zone_pageset(struct zone *zone)
//{
//	int cpu;
//	zone->pageset = alloc_percpu(struct per_cpu_pageset);
//	for_each_possible_cpu(cpu)
//		zone_pageset_init(zone, cpu);
//}

///*
// * Allocate per cpu pagesets and initialize them.
// * Before this call only boot pagesets were available.
// */
//void __init setup_per_cpu_pageset(void)
//{
//	struct pglist_data *pgdat;
//	struct zone *zone;
//	int __maybe_unused cpu;

//	for_each_populated_zone(zone)
//		setup_zone_pageset(zone);

//#ifdef CONFIG_NUMA
//	/*
//	 * Unpopulated zones continue using the boot pagesets.
//	 * The numa stats for these pagesets need to be reset.
//	 * Otherwise, they will end up skewing the stats of
//	 * the nodes these zones are associated with.
//	 */
//	for_each_possible_cpu(cpu) {
//		struct per_cpu_pageset *pcp = &per_cpu(boot_pageset, cpu);
//		memset(pcp->vm_numa_stat_diff, 0,
//		       sizeof(pcp->vm_numa_stat_diff));
//	}
//#endif

//	for_each_online_pgdat(pgdat)
//		pgdat->per_cpu_nodestats =
//			alloc_percpu(struct per_cpu_nodestat);
//}

//static __meminit void zone_pcp_init(struct zone *zone)
//{
//	/*
//	 * per cpu subsystem is not up at this point. The following code
//	 * relies on the ability of the linker to provide the
//	 * offset of a (static) per cpu variable into the per cpu area.
//	 */
//	zone->pageset = &boot_pageset;

//	if (populated_zone(zone))
//		printk(KERN_DEBUG "  %s zone: %lu pages, LIFO batch:%u\n",
//			zone->name, zone->present_pages,
//					 zone_batchsize(zone));
//}

//void __meminit init_currently_empty_zone(struct zone *zone,
//					unsigned long zone_start_pfn,
//					unsigned long size)
//{
//	struct pglist_data *pgdat = zone->zone_pgdat;
//	int zone_idx = zone_idx(zone) + 1;

//	if (zone_idx > pgdat->nr_zones)
//		pgdat->nr_zones = zone_idx;

//	zone->zone_start_pfn = zone_start_pfn;

//	mminit_dprintk(MMINIT_TRACE, "memmap_init",
//			"Initialising map node %d zone %lu pfns %lu -> %lu\n",
//			pgdat->node_id,
//			(unsigned long)zone_idx(zone),
//			zone_start_pfn, (zone_start_pfn + size));

//	zone_init_free_lists(zone);
//	zone->initialized = 1;
//}

///**
// * get_pfn_range_for_nid - Return the start and end page frames for a node
// * @nid: The nid to return the range for. If MAX_NUMNODES, the min and max PFN are returned.
// * @start_pfn: Passed by reference. On return, it will have the node start_pfn.
// * @end_pfn: Passed by reference. On return, it will have the node end_pfn.
// *
// * It returns the start and end page frame of a node based on information
// * provided by memblock_set_node(). If called for a node
// * with no available memory, a warning is printed and the start and end
// * PFNs will be 0.
// */
//void __init get_pfn_range_for_nid(unsigned int nid,
//			unsigned long *start_pfn, unsigned long *end_pfn)
//{
//	unsigned long this_start_pfn, this_end_pfn;
//	int i;

//	*start_pfn = -1UL;
//	*end_pfn = 0;

//	for_each_mem_pfn_range(i, nid, &this_start_pfn, &this_end_pfn, NULL) {
//		*start_pfn = min(*start_pfn, this_start_pfn);
//		*end_pfn = max(*end_pfn, this_end_pfn);
//	}

//	if (*start_pfn == -1UL)
//		*start_pfn = 0;
//}

///*
// * This finds a zone that can be used for ZONE_MOVABLE pages. The
// * assumption is made that zones within a node are ordered in monotonic
// * increasing memory addresses so that the "highest" populated zone is used
// */
//static void __init find_usable_zone_for_movable(void)
//{
//	int zone_index;
//	for (zone_index = MAX_NR_ZONES - 1; zone_index >= 0; zone_index--) {
//		if (zone_index == ZONE_MOVABLE)
//			continue;

//		if (arch_zone_highest_possible_pfn[zone_index] >
//				arch_zone_lowest_possible_pfn[zone_index])
//			break;
//	}

//	VM_BUG_ON(zone_index == -1);
//	movable_zone = zone_index;
//}

///*
// * The zone ranges provided by the architecture do not include ZONE_MOVABLE
// * because it is sized independent of architecture. Unlike the other zones,
// * the starting point for ZONE_MOVABLE is not fixed. It may be different
// * in each node depending on the size of each node and how evenly kernelcore
// * is distributed. This helper function adjusts the zone ranges
// * provided by the architecture for a given node by using the end of the
// * highest usable zone for ZONE_MOVABLE. This preserves the assumption that
// * zones within a node are in order of monotonic increases memory addresses
// */
//static void __init adjust_zone_range_for_zone_movable(int nid,
//					unsigned long zone_type,
//					unsigned long node_start_pfn,
//					unsigned long node_end_pfn,
//					unsigned long *zone_start_pfn,
//					unsigned long *zone_end_pfn)
//{
//	/* Only adjust if ZONE_MOVABLE is on this node */
//	if (zone_movable_pfn[nid]) {
//		/* Size ZONE_MOVABLE */
//		if (zone_type == ZONE_MOVABLE) {
//			*zone_start_pfn = zone_movable_pfn[nid];
//			*zone_end_pfn = min(node_end_pfn,
//				arch_zone_highest_possible_pfn[movable_zone]);

//		/* Adjust for ZONE_MOVABLE starting within this range */
//		} else if (!mirrored_kernelcore &&
//			*zone_start_pfn < zone_movable_pfn[nid] &&
//			*zone_end_pfn > zone_movable_pfn[nid]) {
//			*zone_end_pfn = zone_movable_pfn[nid];

//		/* Check if this whole range is within ZONE_MOVABLE */
//		} else if (*zone_start_pfn >= zone_movable_pfn[nid])
//			*zone_start_pfn = *zone_end_pfn;
//	}
//}

///*
// * Return the number of pages a zone spans in a node, including holes
// * present_pages = zone_spanned_pages_in_node() - zone_absent_pages_in_node()
// */
//static unsigned long __init zone_spanned_pages_in_node(int nid,
//					unsigned long zone_type,
//					unsigned long node_start_pfn,
//					unsigned long node_end_pfn,
//					unsigned long *zone_start_pfn,
//					unsigned long *zone_end_pfn)
//{
//	unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
//	unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
//	/* When hotadd a new node from cpu_up(), the node should be empty */
//	if (!node_start_pfn && !node_end_pfn)
//		return 0;

//	/* Get the start and end of the zone */
//	*zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
//	*zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);
//	adjust_zone_range_for_zone_movable(nid, zone_type,
//				node_start_pfn, node_end_pfn,
//				zone_start_pfn, zone_end_pfn);

//	/* Check that this node has pages within the zone's required range */
//	if (*zone_end_pfn < node_start_pfn || *zone_start_pfn > node_end_pfn)
//		return 0;

//	/* Move the zone boundaries inside the node if necessary */
//	*zone_end_pfn = min(*zone_end_pfn, node_end_pfn);
//	*zone_start_pfn = max(*zone_start_pfn, node_start_pfn);

//	/* Return the spanned pages */
//	return *zone_end_pfn - *zone_start_pfn;
//}

///*
// * Return the number of holes in a range on a node. If nid is MAX_NUMNODES,
// * then all holes in the requested range will be accounted for.
// */
//unsigned long __init __absent_pages_in_range(int nid,
//				unsigned long range_start_pfn,
//				unsigned long range_end_pfn)
//{
//	unsigned long nr_absent = range_end_pfn - range_start_pfn;
//	unsigned long start_pfn, end_pfn;
//	int i;

//	for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
//		start_pfn = clamp(start_pfn, range_start_pfn, range_end_pfn);
//		end_pfn = clamp(end_pfn, range_start_pfn, range_end_pfn);
//		nr_absent -= end_pfn - start_pfn;
//	}
//	return nr_absent;
//}

///**
// * absent_pages_in_range - Return number of page frames in holes within a range
// * @start_pfn: The start PFN to start searching for holes
// * @end_pfn: The end PFN to stop searching for holes
// *
// * Return: the number of pages frames in memory holes within a range.
// */
//unsigned long __init absent_pages_in_range(unsigned long start_pfn,
//							unsigned long end_pfn)
//{
//	return __absent_pages_in_range(MAX_NUMNODES, start_pfn, end_pfn);
//}

///* Return the number of page frames in holes in a zone on a node */
//static unsigned long __init zone_absent_pages_in_node(int nid,
//					unsigned long zone_type,
//					unsigned long node_start_pfn,
//					unsigned long node_end_pfn)
//{
//	unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
//	unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
//	unsigned long zone_start_pfn, zone_end_pfn;
//	unsigned long nr_absent;

//	/* When hotadd a new node from cpu_up(), the node should be empty */
//	if (!node_start_pfn && !node_end_pfn)
//		return 0;

//	zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
//	zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);

//	adjust_zone_range_for_zone_movable(nid, zone_type,
//			node_start_pfn, node_end_pfn,
//			&zone_start_pfn, &zone_end_pfn);
//	nr_absent = __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);

//	/*
//	 * ZONE_MOVABLE handling.
//	 * Treat pages to be ZONE_MOVABLE in ZONE_NORMAL as absent pages
//	 * and vice versa.
//	 */
//	if (mirrored_kernelcore && zone_movable_pfn[nid]) {
//		unsigned long start_pfn, end_pfn;
//		struct memblock_region *r;

//		for_each_mem_region(r) {
//			start_pfn = clamp(memblock_region_memory_base_pfn(r),
//					  zone_start_pfn, zone_end_pfn);
//			end_pfn = clamp(memblock_region_memory_end_pfn(r),
//					zone_start_pfn, zone_end_pfn);

//			if (zone_type == ZONE_MOVABLE &&
//			    memblock_is_mirror(r))
//				nr_absent += end_pfn - start_pfn;

//			if (zone_type == ZONE_NORMAL &&
//			    !memblock_is_mirror(r))
//				nr_absent += end_pfn - start_pfn;
//		}
//	}

//	return nr_absent;
//}

//static void __init calculate_node_totalpages(struct pglist_data *pgdat,
//						unsigned long node_start_pfn,
//						unsigned long node_end_pfn)
//{
//	unsigned long realtotalpages = 0, totalpages = 0;
//	enum zone_type i;

//	for (i = 0; i < MAX_NR_ZONES; i++) {
//		struct zone *zone = pgdat->node_zones + i;
//		unsigned long zone_start_pfn, zone_end_pfn;
//		unsigned long spanned, absent;
//		unsigned long size, real_size;

//		spanned = zone_spanned_pages_in_node(pgdat->node_id, i,
//						     node_start_pfn,
//						     node_end_pfn,
//						     &zone_start_pfn,
//						     &zone_end_pfn);
//		absent = zone_absent_pages_in_node(pgdat->node_id, i,
//						   node_start_pfn,
//						   node_end_pfn);

//		size = spanned;
//		real_size = size - absent;

//		if (size)
//			zone->zone_start_pfn = zone_start_pfn;
//		else
//			zone->zone_start_pfn = 0;
//		zone->spanned_pages = size;
//		zone->present_pages = real_size;

//		totalpages += size;
//		realtotalpages += real_size;
//	}

//	pgdat->node_spanned_pages = totalpages;
//	pgdat->node_present_pages = realtotalpages;
//	printk(KERN_DEBUG "On node %d totalpages: %lu\n", pgdat->node_id,
//							realtotalpages);
//}

//#ifndef CONFIG_SPARSEMEM
///*
// * Calculate the size of the zone->blockflags rounded to an unsigned long
// * Start by making sure zonesize is a multiple of pageblock_order by rounding
// * up. Then use 1 NR_PAGEBLOCK_BITS worth of bits per pageblock, finally
// * round what is now in bits to nearest long in bits, then return it in
// * bytes.
// */
//static unsigned long __init usemap_size(unsigned long zone_start_pfn, unsigned long zonesize)
//{
//	unsigned long usemapsize;

//	zonesize += zone_start_pfn & (pageblock_nr_pages-1);
//	usemapsize = roundup(zonesize, pageblock_nr_pages);
//	usemapsize = usemapsize >> pageblock_order;
//	usemapsize *= NR_PAGEBLOCK_BITS;
//	usemapsize = roundup(usemapsize, 8 * sizeof(unsigned long));

//	return usemapsize / 8;
//}

//static void __ref setup_usemap(struct pglist_data *pgdat,
//				struct zone *zone,
//				unsigned long zone_start_pfn,
//				unsigned long zonesize)
//{
//	unsigned long usemapsize = usemap_size(zone_start_pfn, zonesize);
//	zone->pageblock_flags = NULL;
//	if (usemapsize) {
//		zone->pageblock_flags =
//			memblock_alloc_node(usemapsize, SMP_CACHE_BYTES,
//					    pgdat->node_id);
//		if (!zone->pageblock_flags)
//			panic("Failed to allocate %ld bytes for zone %s pageblock flags on node %d\n",
//			      usemapsize, zone->name, pgdat->node_id);
//	}
//}
//#else
//static inline void setup_usemap(struct pglist_data *pgdat, struct zone *zone,
//				unsigned long zone_start_pfn, unsigned long zonesize) {}
//#endif /* CONFIG_SPARSEMEM */

//#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE

///* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */
//void __init set_pageblock_order(void)
//{
//	unsigned int order;

//	/* Check that pageblock_nr_pages has not already been setup */
//	if (pageblock_order)
//		return;

//	if (HPAGE_SHIFT > PAGE_SHIFT)
//		order = HUGETLB_PAGE_ORDER;
//	else
//		order = MAX_ORDER - 1;

//	/*
//	 * Assume the largest contiguous order of interest is a huge page.
//	 * This value may be variable depending on boot parameters on IA64 and
//	 * powerpc.
//	 */
//	pageblock_order = order;
//}
//#else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */

///*
// * When CONFIG_HUGETLB_PAGE_SIZE_VARIABLE is not set, set_pageblock_order()
// * is unused as pageblock_order is set at compile-time. See
// * include/linux/pageblock-flags.h for the values of pageblock_order based on
// * the kernel config
// */
//void __init set_pageblock_order(void)
//{
//}

//#endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */

//static unsigned long __init calc_memmap_size(unsigned long spanned_pages,
//						unsigned long present_pages)
//{
//	unsigned long pages = spanned_pages;

//	/*
//	 * Provide a more accurate estimation if there are holes within
//	 * the zone and SPARSEMEM is in use. If there are holes within the
//	 * zone, each populated memory region may cost us one or two extra
//	 * memmap pages due to alignment because memmap pages for each
//	 * populated regions may not be naturally aligned on page boundary.
//	 * So the (present_pages >> 4) heuristic is a tradeoff for that.
//	 */
//	if (spanned_pages > present_pages + (present_pages >> 4) &&
//	    IS_ENABLED(CONFIG_SPARSEMEM))
//		pages = present_pages;

//	return PAGE_ALIGN(pages * sizeof(struct page)) >> PAGE_SHIFT;
//}

//#ifdef CONFIG_TRANSPARENT_HUGEPAGE
//static void pgdat_init_split_queue(struct pglist_data *pgdat)
//{
//	struct deferred_split *ds_queue = &pgdat->deferred_split_queue;

//	spin_lock_init(&ds_queue->split_queue_lock);
//	INIT_LIST_HEAD(&ds_queue->split_queue);
//	ds_queue->split_queue_len = 0;
//}
//#else
//static void pgdat_init_split_queue(struct pglist_data *pgdat) {}
//#endif

//#ifdef CONFIG_COMPACTION
//static void pgdat_init_kcompactd(struct pglist_data *pgdat)
//{
//	init_waitqueue_head(&pgdat->kcompactd_wait);
//}
//#else
//static void pgdat_init_kcompactd(struct pglist_data *pgdat) {}
//#endif

//static void __meminit pgdat_init_internals(struct pglist_data *pgdat)
//{
//	pgdat_resize_init(pgdat);

//	pgdat_init_split_queue(pgdat);
//	pgdat_init_kcompactd(pgdat);

//	init_waitqueue_head(&pgdat->kswapd_wait);
//	init_waitqueue_head(&pgdat->pfmemalloc_wait);

//	pgdat_page_ext_init(pgdat);
//	spin_lock_init(&pgdat->lru_lock);
//	lruvec_init(&pgdat->__lruvec);
//}

//static void __meminit zone_init_internals(struct zone *zone, enum zone_type idx, int nid,
//							unsigned long remaining_pages)
//{
//	atomic_long_set(&zone->managed_pages, remaining_pages);
//	zone_set_nid(zone, nid);
//	zone->name = zone_names[idx];
//	zone->zone_pgdat = NODE_DATA(nid);
//	spin_lock_init(&zone->lock);
//	zone_seqlock_init(zone);
//	zone_pcp_init(zone);
//}

///*
// * Set up the zone data structures
// * - init pgdat internals
// * - init all zones belonging to this node
// *
// * NOTE: this function is only called during memory hotplug
// */
//#ifdef CONFIG_MEMORY_HOTPLUG
//void __ref free_area_init_core_hotplug(int nid)
//{
//	enum zone_type z;
//	pg_data_t *pgdat = NODE_DATA(nid);

//	pgdat_init_internals(pgdat);
//	for (z = 0; z < MAX_NR_ZONES; z++)
//		zone_init_internals(&pgdat->node_zones[z], z, nid, 0);
//}
//#endif

///*
// * Set up the zone data structures:
// *   - mark all pages reserved
// *   - mark all memory queues empty
// *   - clear the memory bitmaps
// *
// * NOTE: pgdat should get zeroed by caller.
// * NOTE: this function is only called during early init.
// */
//static void __init free_area_init_core(struct pglist_data *pgdat)
//{
//	enum zone_type j;
//	int nid = pgdat->node_id;

//	pgdat_init_internals(pgdat);
//	pgdat->per_cpu_nodestats = &boot_nodestats;

//	for (j = 0; j < MAX_NR_ZONES; j++) {
//		struct zone *zone = pgdat->node_zones + j;
//		unsigned long size, freesize, memmap_pages;
//		unsigned long zone_start_pfn = zone->zone_start_pfn;

//		size = zone->spanned_pages;
//		freesize = zone->present_pages;

//		/*
//		 * Adjust freesize so that it accounts for how much memory
//		 * is used by this zone for memmap. This affects the watermark
//		 * and per-cpu initialisations
//		 */
//		memmap_pages = calc_memmap_size(size, freesize);
//		if (!is_highmem_idx(j)) {
//			if (freesize >= memmap_pages) {
//				freesize -= memmap_pages;
//				if (memmap_pages)
//					printk(KERN_DEBUG
//					       "  %s zone: %lu pages used for memmap\n",
//					       zone_names[j], memmap_pages);
//			} else
//				pr_warn("  %s zone: %lu pages exceeds freesize %lu\n",
//					zone_names[j], memmap_pages, freesize);
//		}

//		/* Account for reserved pages */
//		if (j == 0 && freesize > dma_reserve) {
//			freesize -= dma_reserve;
//			printk(KERN_DEBUG "  %s zone: %lu pages reserved\n",
//					zone_names[0], dma_reserve);
//		}

//		if (!is_highmem_idx(j))
//			nr_kernel_pages += freesize;
//		/* Charge for highmem memmap if there are enough kernel pages */
//		else if (nr_kernel_pages > memmap_pages * 2)
//			nr_kernel_pages -= memmap_pages;
//		nr_all_pages += freesize;

//		/*
//		 * Set an approximate value for lowmem here, it will be adjusted
//		 * when the bootmem allocator frees pages into the buddy system.
//		 * And all highmem pages will be managed by the buddy system.
//		 */
//		zone_init_internals(zone, j, nid, freesize);

//		if (!size)
//			continue;

//		set_pageblock_order();
//		setup_usemap(pgdat, zone, zone_start_pfn, size);
//		init_currently_empty_zone(zone, zone_start_pfn, size);
//		memmap_init(size, nid, j, zone_start_pfn);
//	}
//}

//#ifdef CONFIG_FLAT_NODE_MEM_MAP
//static void __ref alloc_node_mem_map(struct pglist_data *pgdat)
//{
//	unsigned long __maybe_unused start = 0;
//	unsigned long __maybe_unused offset = 0;

//	/* Skip empty nodes */
//	if (!pgdat->node_spanned_pages)
//		return;

//	start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
//	offset = pgdat->node_start_pfn - start;
//	/* ia64 gets its own node_mem_map, before this, without bootmem */
//	if (!pgdat->node_mem_map) {
//		unsigned long size, end;
//		struct page *map;

//		/*
//		 * The zone's endpoints aren't required to be MAX_ORDER
//		 * aligned but the node_mem_map endpoints must be in order
//		 * for the buddy allocator to function correctly.
//		 */
//		end = pgdat_end_pfn(pgdat);
//		end = ALIGN(end, MAX_ORDER_NR_PAGES);
//		size =  (end - start) * sizeof(struct page);
//		map = memblock_alloc_node(size, SMP_CACHE_BYTES,
//					  pgdat->node_id);
//		if (!map)
//			panic("Failed to allocate %ld bytes for node %d memory map\n",
//			      size, pgdat->node_id);
//		pgdat->node_mem_map = map + offset;
//	}
//	pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
//				__func__, pgdat->node_id, (unsigned long)pgdat,
//				(unsigned long)pgdat->node_mem_map);
//#ifndef CONFIG_NEED_MULTIPLE_NODES
//	/*
//	 * With no DISCONTIG, the global mem_map is just set as node 0's
//	 */
//	if (pgdat == NODE_DATA(0)) {
//		mem_map = NODE_DATA(0)->node_mem_map;
//		if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
//			mem_map -= offset;
//	}
//#endif
//}
//#else
//static void __ref alloc_node_mem_map(struct pglist_data *pgdat) { }
//#endif /* CONFIG_FLAT_NODE_MEM_MAP */

//#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
//static inline void pgdat_set_deferred_range(pg_data_t *pgdat)
//{
//	pgdat->first_deferred_pfn = ULONG_MAX;
//}
//#else
//static inline void pgdat_set_deferred_range(pg_data_t *pgdat) {}
//#endif

//static void __init free_area_init_node(int nid)
//{
//	pg_data_t *pgdat = NODE_DATA(nid);
//	unsigned long start_pfn = 0;
//	unsigned long end_pfn = 0;

//	/* pg_data_t should be reset to zero when it's allocated */
//	WARN_ON(pgdat->nr_zones || pgdat->kswapd_highest_zoneidx);

//	get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);

//	pgdat->node_id = nid;
//	pgdat->node_start_pfn = start_pfn;
//	pgdat->per_cpu_nodestats = NULL;

//	pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid,
//		(u64)start_pfn << PAGE_SHIFT,
//		end_pfn ? ((u64)end_pfn << PAGE_SHIFT) - 1 : 0);
//	calculate_node_totalpages(pgdat, start_pfn, end_pfn);

//	alloc_node_mem_map(pgdat);
//	pgdat_set_deferred_range(pgdat);

//	free_area_init_core(pgdat);
//}

//void __init free_area_init_memoryless_node(int nid)
//{
//	free_area_init_node(nid);
//}

//#if MAX_NUMNODES > 1
///*
// * Figure out the number of possible node ids.
// */
//void __init setup_nr_node_ids(void)
//{
//	unsigned int highest;

//	highest = find_last_bit(node_possible_map.bits, MAX_NUMNODES);
//	nr_node_ids = highest + 1;
//}
//#endif

///**
// * node_map_pfn_alignment - determine the maximum internode alignment
// *
// * This function should be called after node map is populated and sorted.
// * It calculates the maximum power of two alignment which can distinguish
// * all the nodes.
// *
// * For example, if all nodes are 1GiB and aligned to 1GiB, the return value
// * would indicate 1GiB alignment with (1 << (30 - PAGE_SHIFT)).  If the
// * nodes are shifted by 256MiB, 256MiB.  Note that if only the last node is
// * shifted, 1GiB is enough and this function will indicate so.
// *
// * This is used to test whether pfn -> nid mapping of the chosen memory
// * model has fine enough granularity to avoid incorrect mapping for the
// * populated node map.
// *
// * Return: the determined alignment in pfn's.  0 if there is no alignment
// * requirement (single node).
// */
//unsigned long __init node_map_pfn_alignment(void)
//{
//	unsigned long accl_mask = 0, last_end = 0;
//	unsigned long start, end, mask;
//	int last_nid = NUMA_NO_NODE;
//	int i, nid;

//	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid) {
//		if (!start || last_nid < 0 || last_nid == nid) {
//			last_nid = nid;
//			last_end = end;
//			continue;
//		}

//		/*
//		 * Start with a mask granular enough to pin-point to the
//		 * start pfn and tick off bits one-by-one until it becomes
//		 * too coarse to separate the current node from the last.
//		 */
//		mask = ~((1 << __ffs(start)) - 1);
//		while (mask && last_end <= (start & (mask << 1)))
//			mask <<= 1;

//		/* accumulate all internode masks */
//		accl_mask |= mask;
//	}

//	/* convert mask to number of pages */
//	return ~accl_mask + 1;
//}

///**
// * find_min_pfn_with_active_regions - Find the minimum PFN registered
// *
// * Return: the minimum PFN based on information provided via
// * memblock_set_node().
// */
//unsigned long __init find_min_pfn_with_active_regions(void)
//{
//	return PHYS_PFN(memblock_start_of_DRAM());
//}

///*
// * early_calculate_totalpages()
// * Sum pages in active regions for movable zone.
// * Populate N_MEMORY for calculating usable_nodes.
// */
//static unsigned long __init early_calculate_totalpages(void)
//{
//	unsigned long totalpages = 0;
//	unsigned long start_pfn, end_pfn;
//	int i, nid;

//	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
//		unsigned long pages = end_pfn - start_pfn;

//		totalpages += pages;
//		if (pages)
//			node_set_state(nid, N_MEMORY);
//	}
//	return totalpages;
//}

///*
// * Find the PFN the Movable zone begins in each node. Kernel memory
// * is spread evenly between nodes as long as the nodes have enough
// * memory. When they don't, some nodes will have more kernelcore than
// * others
// */
//static void __init find_zone_movable_pfns_for_nodes(void)
//{
//	int i, nid;
//	unsigned long usable_startpfn;
//	unsigned long kernelcore_node, kernelcore_remaining;
//	/* save the state before borrow the nodemask */
//	nodemask_t saved_node_state = node_states[N_MEMORY];
//	unsigned long totalpages = early_calculate_totalpages();
//	int usable_nodes = nodes_weight(node_states[N_MEMORY]);
//	struct memblock_region *r;

//	/* Need to find movable_zone earlier when movable_node is specified. */
//	find_usable_zone_for_movable();

//	/*
//	 * If movable_node is specified, ignore kernelcore and movablecore
//	 * options.
//	 */
//	if (movable_node_is_enabled()) {
//		for_each_mem_region(r) {
//			if (!memblock_is_hotpluggable(r))
//				continue;

//			nid = memblock_get_region_node(r);

//			usable_startpfn = PFN_DOWN(r->base);
//			zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
//				min(usable_startpfn, zone_movable_pfn[nid]) :
//				usable_startpfn;
//		}

//		goto out2;
//	}

//	/*
//	 * If kernelcore=mirror is specified, ignore movablecore option
//	 */
//	if (mirrored_kernelcore) {
//		bool mem_below_4gb_not_mirrored = false;

//		for_each_mem_region(r) {
//			if (memblock_is_mirror(r))
//				continue;

//			nid = memblock_get_region_node(r);

//			usable_startpfn = memblock_region_memory_base_pfn(r);

//			if (usable_startpfn < 0x100000) {
//				mem_below_4gb_not_mirrored = true;
//				continue;
//			}

//			zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
//				min(usable_startpfn, zone_movable_pfn[nid]) :
//				usable_startpfn;
//		}

//		if (mem_below_4gb_not_mirrored)
//			pr_warn("This configuration results in unmirrored kernel memory.\n");

//		goto out2;
//	}

//	/*
//	 * If kernelcore=nn% or movablecore=nn% was specified, calculate the
//	 * amount of necessary memory.
//	 */
//	if (required_kernelcore_percent)
//		required_kernelcore = (totalpages * 100 * required_kernelcore_percent) /
//				       10000UL;
//	if (required_movablecore_percent)
//		required_movablecore = (totalpages * 100 * required_movablecore_percent) /
//					10000UL;

//	/*
//	 * If movablecore= was specified, calculate what size of
//	 * kernelcore that corresponds so that memory usable for
//	 * any allocation type is evenly spread. If both kernelcore
//	 * and movablecore are specified, then the value of kernelcore
//	 * will be used for required_kernelcore if it's greater than
//	 * what movablecore would have allowed.
//	 */
//	if (required_movablecore) {
//		unsigned long corepages;

//		/*
//		 * Round-up so that ZONE_MOVABLE is at least as large as what
//		 * was requested by the user
//		 */
//		required_movablecore =
//			roundup(required_movablecore, MAX_ORDER_NR_PAGES);
//		required_movablecore = min(totalpages, required_movablecore);
//		corepages = totalpages - required_movablecore;

//		required_kernelcore = max(required_kernelcore, corepages);
//	}

//	/*
//	 * If kernelcore was not specified or kernelcore size is larger
//	 * than totalpages, there is no ZONE_MOVABLE.
//	 */
//	if (!required_kernelcore || required_kernelcore >= totalpages)
//		goto out;

//	/* usable_startpfn is the lowest possible pfn ZONE_MOVABLE can be at */
//	usable_startpfn = arch_zone_lowest_possible_pfn[movable_zone];

//restart:
//	/* Spread kernelcore memory as evenly as possible throughout nodes */
//	kernelcore_node = required_kernelcore / usable_nodes;
//	for_each_node_state(nid, N_MEMORY) {
//		unsigned long start_pfn, end_pfn;

//		/*
//		 * Recalculate kernelcore_node if the division per node
//		 * now exceeds what is necessary to satisfy the requested
//		 * amount of memory for the kernel
//		 */
//		if (required_kernelcore < kernelcore_node)
//			kernelcore_node = required_kernelcore / usable_nodes;

//		/*
//		 * As the map is walked, we track how much memory is usable
//		 * by the kernel using kernelcore_remaining. When it is
//		 * 0, the rest of the node is usable by ZONE_MOVABLE
//		 */
//		kernelcore_remaining = kernelcore_node;

//		/* Go through each range of PFNs within this node */
//		for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
//			unsigned long size_pages;

//			start_pfn = max(start_pfn, zone_movable_pfn[nid]);
//			if (start_pfn >= end_pfn)
//				continue;

//			/* Account for what is only usable for kernelcore */
//			if (start_pfn < usable_startpfn) {
//				unsigned long kernel_pages;
//				kernel_pages = min(end_pfn, usable_startpfn)
//								- start_pfn;

//				kernelcore_remaining -= min(kernel_pages,
//							kernelcore_remaining);
//				required_kernelcore -= min(kernel_pages,
//							required_kernelcore);

//				/* Continue if range is now fully accounted */
//				if (end_pfn <= usable_startpfn) {

//					/*
//					 * Push zone_movable_pfn to the end so
//					 * that if we have to rebalance
//					 * kernelcore across nodes, we will
//					 * not double account here
//					 */
//					zone_movable_pfn[nid] = end_pfn;
//					continue;
//				}
//				start_pfn = usable_startpfn;
//			}

//			/*
//			 * The usable PFN range for ZONE_MOVABLE is from
//			 * start_pfn->end_pfn. Calculate size_pages as the
//			 * number of pages used as kernelcore
//			 */
//			size_pages = end_pfn - start_pfn;
//			if (size_pages > kernelcore_remaining)
//				size_pages = kernelcore_remaining;
//			zone_movable_pfn[nid] = start_pfn + size_pages;

//			/*
//			 * Some kernelcore has been met, update counts and
//			 * break if the kernelcore for this node has been
//			 * satisfied
//			 */
//			required_kernelcore -= min(required_kernelcore,
//								size_pages);
//			kernelcore_remaining -= size_pages;
//			if (!kernelcore_remaining)
//				break;
//		}
//	}

//	/*
//	 * If there is still required_kernelcore, we do another pass with one
//	 * less node in the count. This will push zone_movable_pfn[nid] further
//	 * along on the nodes that still have memory until kernelcore is
//	 * satisfied
//	 */
//	usable_nodes--;
//	if (usable_nodes && required_kernelcore > usable_nodes)
//		goto restart;

//out2:
//	/* Align start of ZONE_MOVABLE on all nids to MAX_ORDER_NR_PAGES */
//	for (nid = 0; nid < MAX_NUMNODES; nid++)
//		zone_movable_pfn[nid] =
//			roundup(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES);

//out:
//	/* restore the node_state */
//	node_states[N_MEMORY] = saved_node_state;
//}

///* Any regular or high memory on that node ? */
//static void check_for_memory(pg_data_t *pgdat, int nid)
//{
//	enum zone_type zone_type;

//	for (zone_type = 0; zone_type <= ZONE_MOVABLE - 1; zone_type++) {
//		struct zone *zone = &pgdat->node_zones[zone_type];
//		if (populated_zone(zone)) {
//			if (IS_ENABLED(CONFIG_HIGHMEM))
//				node_set_state(nid, N_HIGH_MEMORY);
//			if (zone_type <= ZONE_NORMAL)
//				node_set_state(nid, N_NORMAL_MEMORY);
//			break;
//		}
//	}
//}

///*
// * Some architecturs, e.g. ARC may have ZONE_HIGHMEM below ZONE_NORMAL. For
// * such cases we allow max_zone_pfn sorted in the descending order
// */
//bool __weak arch_has_descending_max_zone_pfns(void)
//{
//	return false;
//}

///**
// * free_area_init - Initialise all pg_data_t and zone data
// * @max_zone_pfn: an array of max PFNs for each zone
// *
// * This will call free_area_init_node() for each active node in the system.
// * Using the page ranges provided by memblock_set_node(), the size of each
// * zone in each node and their holes is calculated. If the maximum PFN
// * between two adjacent zones match, it is assumed that the zone is empty.
// * For example, if arch_max_dma_pfn == arch_max_dma32_pfn, it is assumed
// * that arch_max_dma32_pfn has no pages. It is also assumed that a zone
// * starts where the previous one ended. For example, ZONE_DMA32 starts
// * at arch_max_dma_pfn.
// */
//void __init free_area_init(unsigned long *max_zone_pfn)
//{
//	unsigned long start_pfn, end_pfn;
//	int i, nid, zone;
//	bool descending;

//	/* Record where the zone boundaries are */
//	memset(arch_zone_lowest_possible_pfn, 0,
//				sizeof(arch_zone_lowest_possible_pfn));
//	memset(arch_zone_highest_possible_pfn, 0,
//				sizeof(arch_zone_highest_possible_pfn));

//	start_pfn = find_min_pfn_with_active_regions();
//	descending = arch_has_descending_max_zone_pfns();

//	for (i = 0; i < MAX_NR_ZONES; i++) {
//		if (descending)
//			zone = MAX_NR_ZONES - i - 1;
//		else
//			zone = i;

//		if (zone == ZONE_MOVABLE)
//			continue;

//		end_pfn = max(max_zone_pfn[zone], start_pfn);
//		arch_zone_lowest_possible_pfn[zone] = start_pfn;
//		arch_zone_highest_possible_pfn[zone] = end_pfn;

//		start_pfn = end_pfn;
//	}

//	/* Find the PFNs that ZONE_MOVABLE begins at in each node */
//	memset(zone_movable_pfn, 0, sizeof(zone_movable_pfn));
//	find_zone_movable_pfns_for_nodes();

//	/* Print out the zone ranges */
//	pr_info("Zone ranges:\n");
//	for (i = 0; i < MAX_NR_ZONES; i++) {
//		if (i == ZONE_MOVABLE)
//			continue;
//		pr_info("  %-8s ", zone_names[i]);
//		if (arch_zone_lowest_possible_pfn[i] ==
//				arch_zone_highest_possible_pfn[i])
//			pr_cont("empty\n");
//		else
//			pr_cont("[mem %#018Lx-%#018Lx]\n",
//				(u64)arch_zone_lowest_possible_pfn[i]
//					<< PAGE_SHIFT,
//				((u64)arch_zone_highest_possible_pfn[i]
//					<< PAGE_SHIFT) - 1);
//	}

//	/* Print out the PFNs ZONE_MOVABLE begins at in each node */
//	pr_info("Movable zone start for each node\n");
//	for (i = 0; i < MAX_NUMNODES; i++) {
//		if (zone_movable_pfn[i])
//			pr_info("  Node %d: %#018Lx\n", i,
//			       (u64)zone_movable_pfn[i] << PAGE_SHIFT);
//	}

//	/*
//	 * Print out the early node map, and initialize the
//	 * subsection-map relative to active online memory ranges to
//	 * enable future "sub-section" extensions of the memory map.
//	 */
//	pr_info("Early memory node ranges\n");
//	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
//		pr_info("  node %3d: [mem %#018Lx-%#018Lx]\n", nid,
//			(u64)start_pfn << PAGE_SHIFT,
//			((u64)end_pfn << PAGE_SHIFT) - 1);
//		subsection_map_init(start_pfn, end_pfn - start_pfn);
//	}

//	/* Initialise every node */
//	mminit_verify_pageflags_layout();
//	setup_nr_node_ids();
//	for_each_online_node(nid) {
//		pg_data_t *pgdat = NODE_DATA(nid);
//		free_area_init_node(nid);

//		/* Any memory on that node */
//		if (pgdat->node_present_pages)
//			node_set_state(nid, N_MEMORY);
//		check_for_memory(pgdat, nid);
//	}
//}

//static int __init cmdline_parse_core(char *p, unsigned long *core,
//				     unsigned long *percent)
//{
//	unsigned long long coremem;
//	char *endptr;

//	if (!p)
//		return -EINVAL;

//	/* Value may be a percentage of total memory, otherwise bytes */
//	coremem = simple_strtoull(p, &endptr, 0);
//	if (*endptr == '%') {
//		/* Paranoid check for percent values greater than 100 */
//		WARN_ON(coremem > 100);

//		*percent = coremem;
//	} else {
//		coremem = memparse(p, &p);
//		/* Paranoid check that UL is enough for the coremem value */
//		WARN_ON((coremem >> PAGE_SHIFT) > ULONG_MAX);

//		*core = coremem >> PAGE_SHIFT;
//		*percent = 0UL;
//	}
//	return 0;
//}

///*
// * kernelcore=size sets the amount of memory for use for allocations that
// * cannot be reclaimed or migrated.
// */
//static int __init cmdline_parse_kernelcore(char *p)
//{
//	/* parse kernelcore=mirror */
//	if (parse_option_str(p, "mirror")) {
//		mirrored_kernelcore = true;
//		return 0;
//	}

//	return cmdline_parse_core(p, &required_kernelcore,
//				  &required_kernelcore_percent);
//}

///*
// * movablecore=size sets the amount of memory for use for allocations that
// * can be reclaimed or migrated.
// */
//static int __init cmdline_parse_movablecore(char *p)
//{
//	return cmdline_parse_core(p, &required_movablecore,
//				  &required_movablecore_percent);
//}

//early_param("kernelcore", cmdline_parse_kernelcore);
//early_param("movablecore", cmdline_parse_movablecore);

//void adjust_managed_page_count(struct page *page, long count)
//{
//	atomic_long_add(count, &page_zone(page)->managed_pages);
//	totalram_pages_add(count);
//#ifdef CONFIG_HIGHMEM
//	if (PageHighMem(page))
//		totalhigh_pages_add(count);
//#endif
//}
//EXPORT_SYMBOL(adjust_managed_page_count);

//unsigned long free_reserved_area(void *start, void *end, int poison, const char *s)
//{
//	void *pos;
//	unsigned long pages = 0;

//	start = (void *)PAGE_ALIGN((unsigned long)start);
//	end = (void *)((unsigned long)end & PAGE_MASK);
//	for (pos = start; pos < end; pos += PAGE_SIZE, pages++) {
//		struct page *page = virt_to_page(pos);
//		void *direct_map_addr;

//		/*
//		 * 'direct_map_addr' might be different from 'pos'
//		 * because some architectures' virt_to_page()
//		 * work with aliases.  Getting the direct map
//		 * address ensures that we get a _writeable_
//		 * alias for the memset().
//		 */
//		direct_map_addr = page_address(page);
//		if ((unsigned int)poison <= 0xFF)
//			memset(direct_map_addr, poison, PAGE_SIZE);

//		free_reserved_page(page);
//	}

//	if (pages && s)
//		pr_info("Freeing %s memory: %ldK\n",
//			s, pages << (PAGE_SHIFT - 10));

//	return pages;
//}

//#ifdef	CONFIG_HIGHMEM
//void free_highmem_page(struct page *page)
//{
//	__free_reserved_page(page);
//	totalram_pages_inc();
//	atomic_long_inc(&page_zone(page)->managed_pages);
//	totalhigh_pages_inc();
//}
//#endif


//void __init mem_init_print_info(const char *str)
//{
//	unsigned long physpages, codesize, datasize, rosize, bss_size;
//	unsigned long init_code_size, init_data_size;

//	physpages = get_num_physpages();
//	codesize = _etext - _stext;
//	datasize = _edata - _sdata;
//	rosize = __end_rodata - __start_rodata;
//	bss_size = __bss_stop - __bss_start;
//	init_data_size = __init_end - __init_begin;
//	init_code_size = _einittext - _sinittext;

//	/*
//	 * Detect special cases and adjust section sizes accordingly:
//	 * 1) .init.* may be embedded into .data sections
//	 * 2) .init.text.* may be out of [__init_begin, __init_end],
//	 *    please refer to arch/tile/kernel/vmlinux.lds.S.
//	 * 3) .rodata.* may be embedded into .text or .data sections.
//	 */
//#define adj_init_size(start, end, size, pos, adj) \
//	do { \
//		if (start <= pos && pos < end && size > adj) \
//			size -= adj; \
//	} while (0)

//	adj_init_size(__init_begin, __init_end, init_data_size,
//		     _sinittext, init_code_size);
//	adj_init_size(_stext, _etext, codesize, _sinittext, init_code_size);
//	adj_init_size(_sdata, _edata, datasize, __init_begin, init_data_size);
//	adj_init_size(_stext, _etext, codesize, __start_rodata, rosize);
//	adj_init_size(_sdata, _edata, datasize, __start_rodata, rosize);

//#undef	adj_init_size

//	pr_info("Memory: %luK/%luK available (%luK kernel code, %luK rwdata, %luK rodata, %luK init, %luK bss, %luK reserved, %luK cma-reserved"
//#ifdef	CONFIG_HIGHMEM
//		", %luK highmem"
//#endif
//		"%s%s)\n",
//		nr_free_pages() << (PAGE_SHIFT - 10),
//		physpages << (PAGE_SHIFT - 10),
//		codesize >> 10, datasize >> 10, rosize >> 10,
//		(init_data_size + init_code_size) >> 10, bss_size >> 10,
//		(physpages - totalram_pages() - totalcma_pages) << (PAGE_SHIFT - 10),
//		totalcma_pages << (PAGE_SHIFT - 10),
//#ifdef	CONFIG_HIGHMEM
//		totalhigh_pages() << (PAGE_SHIFT - 10),
//#endif
//		str ? ", " : "", str ? str : "");
//}

///**
// * set_dma_reserve - set the specified number of pages reserved in the first zone
// * @new_dma_reserve: The number of pages to mark reserved
// *
// * The per-cpu batchsize and zone watermarks are determined by managed_pages.
// * In the DMA zone, a significant percentage may be consumed by kernel image
// * and other unfreeable allocations which can skew the watermarks badly. This
// * function may optionally be used to account for unfreeable pages in the
// * first zone (e.g., ZONE_DMA). The effect will be lower watermarks and
// * smaller per-cpu batchsize.
// */
//void __init set_dma_reserve(unsigned long new_dma_reserve)
//{
//	dma_reserve = new_dma_reserve;
//}

//static int page_alloc_cpu_dead(unsigned int cpu)
//{

//	lru_add_drain_cpu(cpu);
//	drain_pages(cpu);

//	/*
//	 * Spill the event counters of the dead processor
//	 * into the current processors event counters.
//	 * This artificially elevates the count of the current
//	 * processor.
//	 */
//	vm_events_fold_cpu(cpu);

//	/*
//	 * Zero the differential counters of the dead processor
//	 * so that the vm statistics are consistent.
//	 *
//	 * This is only okay since the processor is dead and cannot
//	 * race with what we are doing.
//	 */
//	cpu_vm_stats_fold(cpu);
//	return 0;
//}

//#ifdef CONFIG_NUMA
//int hashdist = HASHDIST_DEFAULT;

//static int __init set_hashdist(char *str)
//{
//	if (!str)
//		return 0;
//	hashdist = simple_strtoul(str, &str, 0);
//	return 1;
//}
//__setup("hashdist=", set_hashdist);
//#endif

//void __init page_alloc_init(void)
//{
//	int ret;

//#ifdef CONFIG_NUMA
//	if (num_node_state(N_MEMORY) == 1)
//		hashdist = 0;
//#endif

//	ret = cpuhp_setup_state_nocalls(CPUHP_PAGE_ALLOC_DEAD,
//					"mm/page_alloc:dead", NULL,
//					page_alloc_cpu_dead);
//	WARN_ON(ret < 0);
//}

///*
// * calculate_totalreserve_pages - called when sysctl_lowmem_reserve_ratio
// *	or min_free_kbytes changes.
// */
//static void calculate_totalreserve_pages(void)
//{
//	struct pglist_data *pgdat;
//	unsigned long reserve_pages = 0;
//	enum zone_type i, j;

//	for_each_online_pgdat(pgdat) {

//		pgdat->totalreserve_pages = 0;

//		for (i = 0; i < MAX_NR_ZONES; i++) {
//			struct zone *zone = pgdat->node_zones + i;
//			long max = 0;
//			unsigned long managed_pages = zone_managed_pages(zone);

//			/* Find valid and maximum lowmem_reserve in the zone */
//			for (j = i; j < MAX_NR_ZONES; j++) {
//				if (zone->lowmem_reserve[j] > max)
//					max = zone->lowmem_reserve[j];
//			}

//			/* we treat the high watermark as reserved pages. */
//			max += high_wmark_pages(zone);

//			if (max > managed_pages)
//				max = managed_pages;

//			pgdat->totalreserve_pages += max;

//			reserve_pages += max;
//		}
//	}
//	totalreserve_pages = reserve_pages;
//}

///*
// * setup_per_zone_lowmem_reserve - called whenever
// *	sysctl_lowmem_reserve_ratio changes.  Ensures that each zone
// *	has a correct pages reserved value, so an adequate number of
// *	pages are left in the zone after a successful __alloc_pages().
// */
//static void setup_per_zone_lowmem_reserve(void)
//{
//	struct pglist_data *pgdat;
//	enum zone_type j, idx;

//	for_each_online_pgdat(pgdat) {
//		for (j = 0; j < MAX_NR_ZONES; j++) {
//			struct zone *zone = pgdat->node_zones + j;
//			unsigned long managed_pages = zone_managed_pages(zone);

//			zone->lowmem_reserve[j] = 0;

//			idx = j;
//			while (idx) {
//				struct zone *lower_zone;

//				idx--;
//				lower_zone = pgdat->node_zones + idx;

//				if (!sysctl_lowmem_reserve_ratio[idx] ||
//				    !zone_managed_pages(lower_zone)) {
//					lower_zone->lowmem_reserve[j] = 0;
//					continue;
//				} else {
//					lower_zone->lowmem_reserve[j] =
//						managed_pages / sysctl_lowmem_reserve_ratio[idx];
//				}
//				managed_pages += zone_managed_pages(lower_zone);
//			}
//		}
//	}

//	/* update totalreserve_pages */
//	calculate_totalreserve_pages();
//}

//static void __setup_per_zone_wmarks(void)
//{
//	unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
//	unsigned long lowmem_pages = 0;
//	struct zone *zone;
//	unsigned long flags;

//	/* Calculate total number of !ZONE_HIGHMEM pages */
//	for_each_zone(zone) {
//		if (!is_highmem(zone))
//			lowmem_pages += zone_managed_pages(zone);
//	}

//	for_each_zone(zone) {
//		u64 tmp;

//		spin_lock_irqsave(&zone->lock, flags);
//		tmp = (u64)pages_min * zone_managed_pages(zone);
//		do_div(tmp, lowmem_pages);
//		if (is_highmem(zone)) {
//			/*
//			 * __GFP_HIGH and PF_MEMALLOC allocations usually don't
//			 * need highmem pages, so cap pages_min to a small
//			 * value here.
//			 *
//			 * The WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_MIN)
//			 * deltas control async page reclaim, and so should
//			 * not be capped for highmem.
//			 */
//			unsigned long min_pages;

//			min_pages = zone_managed_pages(zone) / 1024;
//			min_pages = clamp(min_pages, SWAP_CLUSTER_MAX, 128UL);
//			zone->_watermark[WMARK_MIN] = min_pages;
//		} else {
//			/*
//			 * If it's a lowmem zone, reserve a number of pages
//			 * proportionate to the zone's size.
//			 */
//			zone->_watermark[WMARK_MIN] = tmp;
//		}

//		/*
//		 * Set the kswapd watermarks distance according to the
//		 * scale factor in proportion to available memory, but
//		 * ensure a minimum size on small systems.
//		 */
//		tmp = max_t(u64, tmp >> 2,
//			    mult_frac(zone_managed_pages(zone),
//				      watermark_scale_factor, 10000));

//		zone->watermark_boost = 0;
//		zone->_watermark[WMARK_LOW]  = min_wmark_pages(zone) + tmp;
//		zone->_watermark[WMARK_HIGH] = min_wmark_pages(zone) + tmp * 2;

//		spin_unlock_irqrestore(&zone->lock, flags);
//	}

//	/* update totalreserve_pages */
//	calculate_totalreserve_pages();
//}

///**
// * setup_per_zone_wmarks - called when min_free_kbytes changes
// * or when memory is hot-{added|removed}
// *
// * Ensures that the watermark[min,low,high] values for each zone are set
// * correctly with respect to min_free_kbytes.
// */
//void setup_per_zone_wmarks(void)
//{
//	static DEFINE_SPINLOCK(lock);

//	spin_lock(&lock);
//	__setup_per_zone_wmarks();
//	spin_unlock(&lock);
//}

///*
// * Initialise min_free_kbytes.
// *
// * For small machines we want it small (128k min).  For large machines
// * we want it large (256MB max).  But it is not linear, because network
// * bandwidth does not increase linearly with machine size.  We use
// *
// *	min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
// *	min_free_kbytes = sqrt(lowmem_kbytes * 16)
// *
// * which yields
// *
// * 16MB:	512k
// * 32MB:	724k
// * 64MB:	1024k
// * 128MB:	1448k
// * 256MB:	2048k
// * 512MB:	2896k
// * 1024MB:	4096k
// * 2048MB:	5792k
// * 4096MB:	8192k
// * 8192MB:	11584k
// * 16384MB:	16384k
// */
//int __meminit init_per_zone_wmark_min(void)
//{
//	unsigned long lowmem_kbytes;
//	int new_min_free_kbytes;

//	lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10);
//	new_min_free_kbytes = int_sqrt(lowmem_kbytes * 16);

//	if (new_min_free_kbytes > user_min_free_kbytes) {
//		min_free_kbytes = new_min_free_kbytes;
//		if (min_free_kbytes < 128)
//			min_free_kbytes = 128;
//		if (min_free_kbytes > 262144)
//			min_free_kbytes = 262144;
//	} else {
//		pr_warn("min_free_kbytes is not updated to %d because user defined value %d is preferred\n",
//				new_min_free_kbytes, user_min_free_kbytes);
//	}
//	setup_per_zone_wmarks();
//	refresh_zone_stat_thresholds();
//	setup_per_zone_lowmem_reserve();

//#ifdef CONFIG_NUMA
//	setup_min_unmapped_ratio();
//	setup_min_slab_ratio();
//#endif

//	khugepaged_min_free_kbytes_update();

//	return 0;
//}
//postcore_initcall(init_per_zone_wmark_min)

///*
// * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so
// *	that we can call two helper functions whenever min_free_kbytes
// *	changes.
// */
//int min_free_kbytes_sysctl_handler(struct ctl_table *table, int write,
//		void *buffer, size_t *length, loff_t *ppos)
//{
//	int rc;

//	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
//	if (rc)
//		return rc;

//	if (write) {
//		user_min_free_kbytes = min_free_kbytes;
//		setup_per_zone_wmarks();
//	}
//	return 0;
//}

//int watermark_scale_factor_sysctl_handler(struct ctl_table *table, int write,
//		void *buffer, size_t *length, loff_t *ppos)
//{
//	int rc;

//	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
//	if (rc)
//		return rc;

//	if (write)
//		setup_per_zone_wmarks();

//	return 0;
//}

//#ifdef CONFIG_NUMA
//static void setup_min_unmapped_ratio(void)
//{
//	pg_data_t *pgdat;
//	struct zone *zone;

//	for_each_online_pgdat(pgdat)
//		pgdat->min_unmapped_pages = 0;

//	for_each_zone(zone)
//		zone->zone_pgdat->min_unmapped_pages += (zone_managed_pages(zone) *
//						         sysctl_min_unmapped_ratio) / 100;
//}


//int sysctl_min_unmapped_ratio_sysctl_handler(struct ctl_table *table, int write,
//		void *buffer, size_t *length, loff_t *ppos)
//{
//	int rc;

//	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
//	if (rc)
//		return rc;

//	setup_min_unmapped_ratio();

//	return 0;
//}

//static void setup_min_slab_ratio(void)
//{
//	pg_data_t *pgdat;
//	struct zone *zone;

//	for_each_online_pgdat(pgdat)
//		pgdat->min_slab_pages = 0;

//	for_each_zone(zone)
//		zone->zone_pgdat->min_slab_pages += (zone_managed_pages(zone) *
//						     sysctl_min_slab_ratio) / 100;
//}

//int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *table, int write,
//		void *buffer, size_t *length, loff_t *ppos)
//{
//	int rc;

//	rc = proc_dointvec_minmax(table, write, buffer, length, ppos);
//	if (rc)
//		return rc;

//	setup_min_slab_ratio();

//	return 0;
//}
//#endif

///*
// * lowmem_reserve_ratio_sysctl_handler - just a wrapper around
// *	proc_dointvec() so that we can call setup_per_zone_lowmem_reserve()
// *	whenever sysctl_lowmem_reserve_ratio changes.
// *
// * The reserve ratio obviously has absolutely no relation with the
// * minimum watermarks. The lowmem reserve ratio can only make sense
// * if in function of the boot time zone sizes.
// */
//int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *table, int write,
//		void *buffer, size_t *length, loff_t *ppos)
//{
//	int i;

//	proc_dointvec_minmax(table, write, buffer, length, ppos);

//	for (i = 0; i < MAX_NR_ZONES; i++) {
//		if (sysctl_lowmem_reserve_ratio[i] < 1)
//			sysctl_lowmem_reserve_ratio[i] = 0;
//	}

//	setup_per_zone_lowmem_reserve();
//	return 0;
//}

//static void __zone_pcp_update(struct zone *zone)
//{
//	unsigned int cpu;

//	for_each_possible_cpu(cpu)
//		pageset_set_high_and_batch(zone,
//				per_cpu_ptr(zone->pageset, cpu));
//}

///*
// * percpu_pagelist_fraction - changes the pcp->high for each zone on each
// * cpu.  It is the fraction of total pages in each zone that a hot per cpu
// * pagelist can have before it gets flushed back to buddy allocator.
// */
//int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *table, int write,
//		void *buffer, size_t *length, loff_t *ppos)
//{
//	struct zone *zone;
//	int old_percpu_pagelist_fraction;
//	int ret;

//	mutex_lock(&pcp_batch_high_lock);
//	old_percpu_pagelist_fraction = percpu_pagelist_fraction;

//	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
//	if (!write || ret < 0)
//		goto out;

//	/* Sanity checking to avoid pcp imbalance */
//	if (percpu_pagelist_fraction &&
//	    percpu_pagelist_fraction < MIN_PERCPU_PAGELIST_FRACTION) {
//		percpu_pagelist_fraction = old_percpu_pagelist_fraction;
//		ret = -EINVAL;
//		goto out;
//	}

//	/* No change? */
//	if (percpu_pagelist_fraction == old_percpu_pagelist_fraction)
//		goto out;

//	for_each_populated_zone(zone)
//		__zone_pcp_update(zone);
//out:
//	mutex_unlock(&pcp_batch_high_lock);
//	return ret;
//}

//#ifndef __HAVE_ARCH_RESERVED_KERNEL_PAGES
///*
// * Returns the number of pages that arch has reserved but
// * is not known to alloc_large_system_hash().
// */
//static unsigned long __init arch_reserved_kernel_pages(void)
//{
//	return 0;
//}
//#endif

///*
// * Adaptive scale is meant to reduce sizes of hash tables on large memory
// * machines. As memory size is increased the scale is also increased but at
// * slower pace.  Starting from ADAPT_SCALE_BASE (64G), every time memory
// * quadruples the scale is increased by one, which means the size of hash table
// * only doubles, instead of quadrupling as well.
// * Because 32-bit systems cannot have large physical memory, where this scaling
// * makes sense, it is disabled on such platforms.
// */
//#if __BITS_PER_LONG > 32
//#define ADAPT_SCALE_BASE	(64ul << 30)
//#define ADAPT_SCALE_SHIFT	2
//#define ADAPT_SCALE_NPAGES	(ADAPT_SCALE_BASE >> PAGE_SHIFT)
//#endif

///*
// * allocate a large system hash table from bootmem
// * - it is assumed that the hash table must contain an exact power-of-2
// *   quantity of entries
// * - limit is the number of hash buckets, not the total allocation size
// */
//void *__init alloc_large_system_hash(const char *tablename,
//				     unsigned long bucketsize,
//				     unsigned long numentries,
//				     int scale,
//				     int flags,
//				     unsigned int *_hash_shift,
//				     unsigned int *_hash_mask,
//				     unsigned long low_limit,
//				     unsigned long high_limit)
//{
//	unsigned long long max = high_limit;
//	unsigned long log2qty, size;
//	void *table = NULL;
//	gfp_t gfp_flags;
//	bool virt;

//	/* allow the kernel cmdline to have a say */
//	if (!numentries) {
//		/* round applicable memory size up to nearest megabyte */
//		numentries = nr_kernel_pages;
//		numentries -= arch_reserved_kernel_pages();

//		/* It isn't necessary when PAGE_SIZE >= 1MB */
//		if (PAGE_SHIFT < 20)
//			numentries = round_up(numentries, (1<<20)/PAGE_SIZE);

//#if __BITS_PER_LONG > 32
//		if (!high_limit) {
//			unsigned long adapt;

//			for (adapt = ADAPT_SCALE_NPAGES; adapt < numentries;
//			     adapt <<= ADAPT_SCALE_SHIFT)
//				scale++;
//		}
//#endif

//		/* limit to 1 bucket per 2^scale bytes of low memory */
//		if (scale > PAGE_SHIFT)
//			numentries >>= (scale - PAGE_SHIFT);
//		else
//			numentries <<= (PAGE_SHIFT - scale);

//		/* Make sure we've got at least a 0-order allocation.. */
//		if (unlikely(flags & HASH_SMALL)) {
//			/* Makes no sense without HASH_EARLY */
//			WARN_ON(!(flags & HASH_EARLY));
//			if (!(numentries >> *_hash_shift)) {
//				numentries = 1UL << *_hash_shift;
//				BUG_ON(!numentries);
//			}
//		} else if (unlikely((numentries * bucketsize) < PAGE_SIZE))
//			numentries = PAGE_SIZE / bucketsize;
//	}
//	numentries = roundup_pow_of_two(numentries);

//	/* limit allocation size to 1/16 total memory by default */
//	if (max == 0) {
//		max = ((unsigned long long)nr_all_pages << PAGE_SHIFT) >> 4;
//		do_div(max, bucketsize);
//	}
//	max = min(max, 0x80000000ULL);

//	if (numentries < low_limit)
//		numentries = low_limit;
//	if (numentries > max)
//		numentries = max;

//	log2qty = ilog2(numentries);

//	gfp_flags = (flags & HASH_ZERO) ? GFP_ATOMIC | __GFP_ZERO : GFP_ATOMIC;
//	do {
//		virt = false;
//		size = bucketsize << log2qty;
//		if (flags & HASH_EARLY) {
//			if (flags & HASH_ZERO)
//				table = memblock_alloc(size, SMP_CACHE_BYTES);
//			else
//				table = memblock_alloc_raw(size,
//							   SMP_CACHE_BYTES);
//		} else if (get_order(size) >= MAX_ORDER || hashdist) {
//			table = __vmalloc(size, gfp_flags);
//			virt = true;
//		} else {
//			/*
//			 * If bucketsize is not a power-of-two, we may free
//			 * some pages at the end of hash table which
//			 * alloc_pages_exact() automatically does
//			 */
//			table = alloc_pages_exact(size, gfp_flags);
//			kmemleak_alloc(table, size, 1, gfp_flags);
//		}
//	} while (!table && size > PAGE_SIZE && --log2qty);

//	if (!table)
//		panic("Failed to allocate %s hash table\n", tablename);

//	pr_info("%s hash table entries: %ld (order: %d, %lu bytes, %s)\n",
//		tablename, 1UL << log2qty, ilog2(size) - PAGE_SHIFT, size,
//		virt ? "vmalloc" : "linear");

//	if (_hash_shift)
//		*_hash_shift = log2qty;
//	if (_hash_mask)
//		*_hash_mask = (1 << log2qty) - 1;

//	return table;
//}

///*
// * This function checks whether pageblock includes unmovable pages or not.
// *
// * PageLRU check without isolation or lru_lock could race so that
// * MIGRATE_MOVABLE block might include unmovable pages. And __PageMovable
// * check without lock_page also may miss some movable non-lru pages at
// * race condition. So you can't expect this function should be exact.
// *
// * Returns a page without holding a reference. If the caller wants to
// * dereference that page (e.g., dumping), it has to make sure that it
// * cannot get removed (e.g., via memory unplug) concurrently.
// *
// */
//struct page *has_unmovable_pages(struct zone *zone, struct page *page,
//				 int migratetype, int flags)
//{
//	unsigned long iter = 0;
//	unsigned long pfn = page_to_pfn(page);
//	unsigned long offset = pfn % pageblock_nr_pages;

//	if (is_migrate_cma_page(page)) {
//		/*
//		 * CMA allocations (alloc_contig_range) really need to mark
//		 * isolate CMA pageblocks even when they are not movable in fact
//		 * so consider them movable here.
//		 */
//		if (is_migrate_cma(migratetype))
//			return NULL;

//		return page;
//	}

//	for (; iter < pageblock_nr_pages - offset; iter++) {
//		if (!pfn_valid_within(pfn + iter))
//			continue;

//		page = pfn_to_page(pfn + iter);

//		/*
//		 * Both, bootmem allocations and memory holes are marked
//		 * PG_reserved and are unmovable. We can even have unmovable
//		 * allocations inside ZONE_MOVABLE, for example when
//		 * specifying "movablecore".
//		 */
//		if (PageReserved(page))
//			return page;

//		/*
//		 * If the zone is movable and we have ruled out all reserved
//		 * pages then it should be reasonably safe to assume the rest
//		 * is movable.
//		 */
//		if (zone_idx(zone) == ZONE_MOVABLE)
//			continue;

//		/*
//		 * Hugepages are not in LRU lists, but they're movable.
//		 * THPs are on the LRU, but need to be counted as #small pages.
//		 * We need not scan over tail pages because we don't
//		 * handle each tail page individually in migration.
//		 */
//		if (PageHuge(page) || PageTransCompound(page)) {
//			struct page *head = compound_head(page);
//			unsigned int skip_pages;

//			if (PageHuge(page)) {
//				if (!hugepage_migration_supported(page_hstate(head)))
//					return page;
//			} else if (!PageLRU(head) && !__PageMovable(head)) {
//				return page;
//			}

//			skip_pages = compound_nr(head) - (page - head);
//			iter += skip_pages - 1;
//			continue;
//		}

//		/*
//		 * We can't use page_count without pin a page
//		 * because another CPU can free compound page.
//		 * This check already skips compound tails of THP
//		 * because their page->_refcount is zero at all time.
//		 */
//		if (!page_ref_count(page)) {
//			if (PageBuddy(page))
//				iter += (1 << buddy_order(page)) - 1;
//			continue;
//		}

//		/*
//		 * The HWPoisoned page may be not in buddy system, and
//		 * page_count() is not 0.
//		 */
//		if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
//			continue;

//		/*
//		 * We treat all PageOffline() pages as movable when offlining
//		 * to give drivers a chance to decrement their reference count
//		 * in MEM_GOING_OFFLINE in order to indicate that these pages
//		 * can be offlined as there are no direct references anymore.
//		 * For actually unmovable PageOffline() where the driver does
//		 * not support this, we will fail later when trying to actually
//		 * move these pages that still have a reference count > 0.
//		 * (false negatives in this function only)
//		 */
//		if ((flags & MEMORY_OFFLINE) && PageOffline(page))
//			continue;

//		if (__PageMovable(page) || PageLRU(page))
//			continue;

//		/*
//		 * If there are RECLAIMABLE pages, we need to check
//		 * it.  But now, memory offline itself doesn't call
//		 * shrink_node_slabs() and it still to be fixed.
//		 */
//		return page;
//	}
//	return NULL;
//}

//#ifdef CONFIG_CONTIG_ALLOC
//static unsigned long pfn_max_align_down(unsigned long pfn)
//{
//	return pfn & ~(max_t(unsigned long, MAX_ORDER_NR_PAGES,
//			     pageblock_nr_pages) - 1);
//}

//static unsigned long pfn_max_align_up(unsigned long pfn)
//{
//	return ALIGN(pfn, max_t(unsigned long, MAX_ORDER_NR_PAGES,
//				pageblock_nr_pages));
//}

///* [start, end) must belong to a single zone. */
//static int __alloc_contig_migrate_range(struct compact_control *cc,
//					unsigned long start, unsigned long end)
//{
//	/* This function is based on compact_zone() from compaction.c. */
//	unsigned int nr_reclaimed;
//	unsigned long pfn = start;
//	unsigned int tries = 0;
//	int ret = 0;
//	struct migration_target_control mtc = {
//		.nid = zone_to_nid(cc->zone),
//		.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
//	};

//	migrate_prep();

//	while (pfn < end || !list_empty(&cc->migratepages)) {
//		if (fatal_signal_pending(current)) {
//			ret = -EINTR;
//			break;
//		}

//		if (list_empty(&cc->migratepages)) {
//			cc->nr_migratepages = 0;
//			pfn = isolate_migratepages_range(cc, pfn, end);
//			if (!pfn) {
//				ret = -EINTR;
//				break;
//			}
//			tries = 0;
//		} else if (++tries == 5) {
//			ret = ret < 0 ? ret : -EBUSY;
//			break;
//		}

//		nr_reclaimed = reclaim_clean_pages_from_list(cc->zone,
//							&cc->migratepages);
//		cc->nr_migratepages -= nr_reclaimed;

//		ret = migrate_pages(&cc->migratepages, alloc_migration_target,
//				NULL, (unsigned long)&mtc, cc->mode, MR_CONTIG_RANGE);
//	}
//	if (ret < 0) {
//		putback_movable_pages(&cc->migratepages);
//		return ret;
//	}
//	return 0;
//}

///**
// * alloc_contig_range() -- tries to allocate given range of pages
// * @start:	start PFN to allocate
// * @end:	one-past-the-last PFN to allocate
// * @migratetype:	migratetype of the underlaying pageblocks (either
// *			#MIGRATE_MOVABLE or #MIGRATE_CMA).  All pageblocks
// *			in range must have the same migratetype and it must
// *			be either of the two.
// * @gfp_mask:	GFP mask to use during compaction
// *
// * The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES
// * aligned.  The PFN range must belong to a single zone.
// *
// * The first thing this routine does is attempt to MIGRATE_ISOLATE all
// * pageblocks in the range.  Once isolated, the pageblocks should not
// * be modified by others.
// *
// * Return: zero on success or negative error code.  On success all
// * pages which PFN is in [start, end) are allocated for the caller and
// * need to be freed with free_contig_range().
// */
//int alloc_contig_range(unsigned long start, unsigned long end,
//		       unsigned migratetype, gfp_t gfp_mask)
//{
//	unsigned long outer_start, outer_end;
//	unsigned int order;
//	int ret = 0;

//	struct compact_control cc = {
//		.nr_migratepages = 0,
//		.order = -1,
//		.zone = page_zone(pfn_to_page(start)),
//		.mode = MIGRATE_SYNC,
//		.ignore_skip_hint = true,
//		.no_set_skip_hint = true,
//		.gfp_mask = current_gfp_context(gfp_mask),
//		.alloc_contig = true,
//	};
//	INIT_LIST_HEAD(&cc.migratepages);

//	/*
//	 * What we do here is we mark all pageblocks in range as
//	 * MIGRATE_ISOLATE.  Because pageblock and max order pages may
//	 * have different sizes, and due to the way page allocator
//	 * work, we align the range to biggest of the two pages so
//	 * that page allocator won't try to merge buddies from
//	 * different pageblocks and change MIGRATE_ISOLATE to some
//	 * other migration type.
//	 *
//	 * Once the pageblocks are marked as MIGRATE_ISOLATE, we
//	 * migrate the pages from an unaligned range (ie. pages that
//	 * we are interested in).  This will put all the pages in
//	 * range back to page allocator as MIGRATE_ISOLATE.
//	 *
//	 * When this is done, we take the pages in range from page
//	 * allocator removing them from the buddy system.  This way
//	 * page allocator will never consider using them.
//	 *
//	 * This lets us mark the pageblocks back as
//	 * MIGRATE_CMA/MIGRATE_MOVABLE so that free pages in the
//	 * aligned range but not in the unaligned, original range are
//	 * put back to page allocator so that buddy can use them.
//	 */

//	ret = start_isolate_page_range(pfn_max_align_down(start),
//				       pfn_max_align_up(end), migratetype, 0);
//	if (ret)
//		return ret;

//	/*
//	 * In case of -EBUSY, we'd like to know which page causes problem.
//	 * So, just fall through. test_pages_isolated() has a tracepoint
//	 * which will report the busy page.
//	 *
//	 * It is possible that busy pages could become available before
//	 * the call to test_pages_isolated, and the range will actually be
//	 * allocated.  So, if we fall through be sure to clear ret so that
//	 * -EBUSY is not accidentally used or returned to caller.
//	 */
//	ret = __alloc_contig_migrate_range(&cc, start, end);
//	if (ret && ret != -EBUSY)
//		goto done;
//	ret =0;

//	/*
//	 * Pages from [start, end) are within a MAX_ORDER_NR_PAGES
//	 * aligned blocks that are marked as MIGRATE_ISOLATE.  What's
//	 * more, all pages in [start, end) are free in page allocator.
//	 * What we are going to do is to allocate all pages from
//	 * [start, end) (that is remove them from page allocator).
//	 *
//	 * The only problem is that pages at the beginning and at the
//	 * end of interesting range may be not aligned with pages that
//	 * page allocator holds, ie. they can be part of higher order
//	 * pages.  Because of this, we reserve the bigger range and
//	 * once this is done free the pages we are not interested in.
//	 *
//	 * We don't have to hold zone->lock here because the pages are
//	 * isolated thus they won't get removed from buddy.
//	 */

//	lru_add_drain_all();

//	order = 0;
//	outer_start = start;
//	while (!PageBuddy(pfn_to_page(outer_start))) {
//		if (++order >= MAX_ORDER) {
//			outer_start = start;
//			break;
//		}
//		outer_start &= ~0UL << order;
//	}

//	if (outer_start != start) {
//		order = buddy_order(pfn_to_page(outer_start));

//		/*
//		 * outer_start page could be small order buddy page and
//		 * it doesn't include start page. Adjust outer_start
//		 * in this case to report failed page properly
//		 * on tracepoint in test_pages_isolated()
//		 */
//		if (outer_start + (1UL << order) <= start)
//			outer_start = start;
//	}

//	/* Make sure the range is really isolated. */
//	if (test_pages_isolated(outer_start, end, 0)) {
//		pr_info_ratelimited("%s: [%lx, %lx) PFNs busy\n",
//			__func__, outer_start, end);
//		ret = -EBUSY;
//		goto done;
//	}

//	/* Grab isolated pages from freelists. */
//	outer_end = isolate_freepages_range(&cc, outer_start, end);
//	if (!outer_end) {
//		ret = -EBUSY;
//		goto done;
//	}

//	/* Free head and tail (if any) */
//	if (start != outer_start)
//		free_contig_range(outer_start, start - outer_start);
//	if (end != outer_end)
//		free_contig_range(end, outer_end - end);

//done:
//	undo_isolate_page_range(pfn_max_align_down(start),
//				pfn_max_align_up(end), migratetype);
//	return ret;
//}
//EXPORT_SYMBOL(alloc_contig_range);

//static int __alloc_contig_pages(unsigned long start_pfn,
//				unsigned long nr_pages, gfp_t gfp_mask)
//{
//	unsigned long end_pfn = start_pfn + nr_pages;

//	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
//				  gfp_mask);
//}

//static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn,
//				   unsigned long nr_pages)
//{
//	unsigned long i, end_pfn = start_pfn + nr_pages;
//	struct page *page;

//	for (i = start_pfn; i < end_pfn; i++) {
//		page = pfn_to_online_page(i);
//		if (!page)
//			return false;

//		if (page_zone(page) != z)
//			return false;

//		if (PageReserved(page))
//			return false;

//		if (page_count(page) > 0)
//			return false;

//		if (PageHuge(page))
//			return false;
//	}
//	return true;
//}

//static bool zone_spans_last_pfn(const struct zone *zone,
//				unsigned long start_pfn, unsigned long nr_pages)
//{
//	unsigned long last_pfn = start_pfn + nr_pages - 1;

//	return zone_spans_pfn(zone, last_pfn);
//}

///**
// * alloc_contig_pages() -- tries to find and allocate contiguous range of pages
// * @nr_pages:	Number of contiguous pages to allocate
// * @gfp_mask:	GFP mask to limit search and used during compaction
// * @nid:	Target node
// * @nodemask:	Mask for other possible nodes
// *
// * This routine is a wrapper around alloc_contig_range(). It scans over zones
// * on an applicable zonelist to find a contiguous pfn range which can then be
// * tried for allocation with alloc_contig_range(). This routine is intended
// * for allocation requests which can not be fulfilled with the buddy allocator.
// *
// * The allocated memory is always aligned to a page boundary. If nr_pages is a
// * power of two then the alignment is guaranteed to be to the given nr_pages
// * (e.g. 1GB request would be aligned to 1GB).
// *
// * Allocated pages can be freed with free_contig_range() or by manually calling
// * __free_page() on each allocated page.
// *
// * Return: pointer to contiguous pages on success, or NULL if not successful.
// */
//struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t gfp_mask,
//				int nid, nodemask_t *nodemask)
//{
//	unsigned long ret, pfn, flags;
//	struct zonelist *zonelist;
//	struct zone *zone;
//	struct zoneref *z;

//	zonelist = node_zonelist(nid, gfp_mask);
//	for_each_zone_zonelist_nodemask(zone, z, zonelist,
//					gfp_zone(gfp_mask), nodemask) {
//		spin_lock_irqsave(&zone->lock, flags);

//		pfn = ALIGN(zone->zone_start_pfn, nr_pages);
//		while (zone_spans_last_pfn(zone, pfn, nr_pages)) {
//			if (pfn_range_valid_contig(zone, pfn, nr_pages)) {
//				/*
//				 * We release the zone lock here because
//				 * alloc_contig_range() will also lock the zone
//				 * at some point. If there's an allocation
//				 * spinning on this lock, it may win the race
//				 * and cause alloc_contig_range() to fail...
//				 */
//				spin_unlock_irqrestore(&zone->lock, flags);
//				ret = __alloc_contig_pages(pfn, nr_pages,
//							gfp_mask);
//				if (!ret)
//					return pfn_to_page(pfn);
//				spin_lock_irqsave(&zone->lock, flags);
//			}
//			pfn += nr_pages;
//		}
//		spin_unlock_irqrestore(&zone->lock, flags);
//	}
//	return NULL;
//}
//#endif /* CONFIG_CONTIG_ALLOC */

//void free_contig_range(unsigned long pfn, unsigned int nr_pages)
//{
//	unsigned int count = 0;

//	for (; nr_pages--; pfn++) {
//		struct page *page = pfn_to_page(pfn);

//		count += page_count(page) != 1;
//		__free_page(page);
//	}
//	WARN(count != 0, "%d pages are still in use!\n", count);
//}
//EXPORT_SYMBOL(free_contig_range);

///*
// * The zone indicated has a new number of managed_pages; batch sizes and percpu
// * page high values need to be recalulated.
// */
//void __meminit zone_pcp_update(struct zone *zone)
//{
//	mutex_lock(&pcp_batch_high_lock);
//	__zone_pcp_update(zone);
//	mutex_unlock(&pcp_batch_high_lock);
//}

//void zone_pcp_reset(struct zone *zone)
//{
//	unsigned long flags;
//	int cpu;
//	struct per_cpu_pageset *pset;

//	/* avoid races with drain_pages()  */
//	local_irq_save(flags);
//	if (zone->pageset != &boot_pageset) {
//		for_each_online_cpu(cpu) {
//			pset = per_cpu_ptr(zone->pageset, cpu);
//			drain_zonestat(zone, pset);
//		}
//		free_percpu(zone->pageset);
//		zone->pageset = &boot_pageset;
//	}
//	local_irq_restore(flags);
//}

//#ifdef CONFIG_MEMORY_HOTREMOVE
///*
// * All pages in the range must be in a single zone, must not contain holes,
// * must span full sections, and must be isolated before calling this function.
// */
//void __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
//{
//	unsigned long pfn = start_pfn;
//	struct page *page;
//	struct zone *zone;
//	unsigned int order;
//	unsigned long flags;

//	offline_mem_sections(pfn, end_pfn);
//	zone = page_zone(pfn_to_page(pfn));
//	spin_lock_irqsave(&zone->lock, flags);
//	while (pfn < end_pfn) {
//		page = pfn_to_page(pfn);
//		/*
//		 * The HWPoisoned page may be not in buddy system, and
//		 * page_count() is not 0.
//		 */
//		if (unlikely(!PageBuddy(page) && PageHWPoison(page))) {
//			pfn++;
//			continue;
//		}
//		/*
//		 * At this point all remaining PageOffline() pages have a
//		 * reference count of 0 and can simply be skipped.
//		 */
//		if (PageOffline(page)) {
//			BUG_ON(page_count(page));
//			BUG_ON(PageBuddy(page));
//			pfn++;
//			continue;
//		}

//		BUG_ON(page_count(page));
//		BUG_ON(!PageBuddy(page));
//		order = buddy_order(page);
//		del_page_from_free_list(page, zone, order);
//		pfn += (1 << order);
//	}
//	spin_unlock_irqrestore(&zone->lock, flags);
//}
//#endif

//bool is_free_buddy_page(struct page *page)
//{
//	struct zone *zone = page_zone(page);
//	unsigned long pfn = page_to_pfn(page);
//	unsigned long flags;
//	unsigned int order;

//	spin_lock_irqsave(&zone->lock, flags);
//	for (order = 0; order < MAX_ORDER; order++) {
//		struct page *page_head = page - (pfn & ((1 << order) - 1));

//		if (PageBuddy(page_head) && buddy_order(page_head) >= order)
//			break;
//	}
//	spin_unlock_irqrestore(&zone->lock, flags);

//	return order < MAX_ORDER;
//}

//#ifdef CONFIG_MEMORY_FAILURE
///*
// * Break down a higher-order page in sub-pages, and keep our target out of
// * buddy allocator.
// */
//static void break_down_buddy_pages(struct zone *zone, struct page *page,
//				   struct page *target, int low, int high,
//				   int migratetype)
//{
//	unsigned long size = 1 << high;
//	struct page *current_buddy, *next_page;

//	while (high > low) {
//		high--;
//		size >>= 1;

//		if (target >= &page[size]) {
//			next_page = page + size;
//			current_buddy = page;
//		} else {
//			next_page = page;
//			current_buddy = page + size;
//		}

//		if (set_page_guard(zone, current_buddy, high, migratetype))
//			continue;

//		if (current_buddy != target) {
//			add_to_free_list(current_buddy, zone, high, migratetype);
//			set_buddy_order(current_buddy, high);
//			page = next_page;
//		}
//	}
//}

///*
// * Take a page that will be marked as poisoned off the buddy allocator.
// */
//bool take_page_off_buddy(struct page *page)
//{
//	struct zone *zone = page_zone(page);
//	unsigned long pfn = page_to_pfn(page);
//	unsigned long flags;
//	unsigned int order;
//	bool ret = false;

//	spin_lock_irqsave(&zone->lock, flags);
//	for (order = 0; order < MAX_ORDER; order++) {
//		struct page *page_head = page - (pfn & ((1 << order) - 1));
//		int page_order = buddy_order(page_head);

//		if (PageBuddy(page_head) && page_order >= order) {
//			unsigned long pfn_head = page_to_pfn(page_head);
//			int migratetype = get_pfnblock_migratetype(page_head,
//								   pfn_head);

//			del_page_from_free_list(page_head, zone, page_order);
//			break_down_buddy_pages(zone, page_head, page, 0,
//						page_order, migratetype);
//			if (!is_migrate_isolate(migratetype))
//				__mod_zone_freepage_state(zone, -1, migratetype);
//			ret = true;
//			break;
//		}
//		if (page_count(page_head) > 0)
//			break;
//	}
//	spin_unlock_irqrestore(&zone->lock, flags);
//	return ret;
//}
//#endif
